Currently about 18 months and 5 levels out of date. Please do not consider for anything more than generalities (str and con and cha are good, divine sacrifice is good, divine might is good, etc).
Perhaps this will get updated again some day.
Whether you're new to DDO entirely or new to the paladin class, this guide seeks to provide you with good information for creating paladin characters. Established players looking for specific build information might want to page down once or twice, but if you're not really familiar with paladin mechanics, abilities and build decisions, you might as well keep reading from here. This guide is intended to be useful to people who intend to take a majority of their levels in the paladin class. I cannot review every single paladin ability and enhancement; rather, I will review the most important and most frequently misunderstood abilities and enhancements. For a comprehensive overview of paladin feats, spells and enhancements, you should consult the DDO Compendium page, which lists it much more efficiently than I ever could. Similarly, I won't spend a lot of time on the very basics of DDO character creation. Melee characters take toughness because they don't have enough hit points without it.
The main purpose of the guide is to help you create a paladin that will age well into the endgame. Because paladins are very, very powerful at low levels in DDO, it's easy to make one that is strong at low levels and ages badly.
A note: I don't specifically touch on the paladin prestige enhancement lines in the guide (outside of identifying how they are frequently associated with certain kinds of character). This means I don't ever discuss the Hunter of the Dead prestige enhancement line, as its primarily used for leveling and for very creative builds that are interested in it's healing amplification abilities. Its abilities don't really enhance the core focus of generic paladin builds, and so it's difficult to find it a place in the guide. It's almost exclusively used by heavy multiclass builds and levelers prior to level 12.
A hotlink index to parts of the thread:
DPS Paladin Information
Tank Paladin Information
Paladin Healing Information
Weapon Selection & Holy Sword
Links to Advanced Builds
I. The Basics of Paladin Play and Combat
Paladins are one of DDO's most thinly stretched classes statistically. Regardless of build or role, a paladin requires investment in more statistics than a fighter or barbarian designed for a similar job. This is caused in large part because paladins must make very large investments in Charisma to power their offense as well as their basic defensive (Divine Grace) and healing (Lay on Hands) abilities. For this reason, a typical paladin will have less strength and constitution than a barbarian or fighter built for similar combat style, and creating two-weapon fighting paladin builds is incredibly difficult without access to the drow race or 32 point builds. Most paladins use wisdom as their primary dump stat, in defiance of typical D&D logic. Items let you qualify for spell casting on DDO, and depending on your paladins chosen role, he may need to invest in a 12 or higher starting stat in every other statistic! There'll be more information on these kind of tradeoffs in the build examples, but as a general sort of rule you could say that two-handed fighting paladins can dump dex, wis and usually intelligence, two-weapon fighting paladins can drop wisdom and usually intelligence, and tank-based paladins can only drop wisdom. In fact, monk-based tank paladins can't even dump that! Consequently, it's very important to learn how each statistic benefits your character's role.
Strength: Paladins are a feat-starved class, and consequently paladins built around Weapon Finesse are quite rare. Whether a tank or a damage-dealer, strength is critical to your offensive output. While paladins get many buffs and abilities which increase their damage dealing, only a few of these also help their to-hit. Consequently, while you may sacrifice a point or two of strength for other statistics, you still want as much as you can possibly squeeze in.
Dexterity: Dexterity serves two purposes only: It helps two-weapon fighting paladins qualify for the two weapon feats, and a moderate amount is important to tank-based paladins, who want to carefully control their dexterity: You want enough to fill out the max dex bonus of your endgame armor, but anything over that is wasted. The additional reflex saves, while handy, are rarely an issue due to Divine Grace, Aura Bonuses, and etc. Because paladins are so starved for build points and have such good innate saving throws, investment in dexterity for other reasons is not advisable.
Constitution: For every DDO character, constitution is extremely important. This is certainly true on a front-line melee class, even one with great saves and self-healing abilities. Typical advice is to invest in constitution for as long as you get 1 point per 1 build point. Paying 2 for 1 in constitution is rarely a good idea, and some two weapon human, dwarf or warforged builds will go 2 points shy of that (12 human, 14 dwarf/wf). Going under 12 is never wise, and even the listed exception is something you should approach carefully.
Intelligence: Intelligence only has two purposes: skill points and, for tanks, qualifying for Combat Expertise. Most human and drow paladins will not spend any build points on intelligence (unless they are a tank, in whichcase they will start at 11 or 12, depending on build point availability) for CE's requirement of 13. Elf, half orc, dwarf, halfling and warforged builds may feel compelled to put 2 points here in order to get enough skill points to raise something besides the always-important Use Magic Device.
Wisdom: Wisdom fuels paladin spell points and spell-casting. You need to have 10+spell level wisdom to cast. Any paladin that does not depend on monk's wisdom bonus to AC is well advised to not start with more than 8 wisdom. While it will be inconvenient until a +2 or 3 wisdom item is found, the additional spell points are never consequential and pretty much every other stat is important. It may be that this means you cannot cast spells initially when you acquire them at level 4 for a level or two. While this is obnoxious, it's important to remember that if you did have enough wisdom to cast them, you'd have 20-25 spell points and be able to cast them once or twice per shrine. Most new players see that tomes are used for wisdom and assume they can't dump stat it, and it's certainly an inconvenience, but it's one that will wear off by level 11, and for which you'll be glad from about level 13 upward. It doesn't take having tomes to make dumping wisdom wise, just a bit of patience. The House Phiarlan favor wisdom buff can be used to enable your spellcasting from level 5 until you locate a decent wisdom item. Since your spells at that level are quite weak until you reach level 9, you're not very disadvantaged should you die and lose the buff.
Charisma: Charisma is incredibly important to the paladin in all areas of combat. In addition to getting their charisma modifier added to all saves (Divine Grace), Lay on Hands heals (10 + paladin level) * charisma modifier hit points instantly and with no interrupt chance. You can have as many as 4 (5, as a defender) lay on hands. Lastly, the most important paladin damage-dealing enhancement depends on your base charisma. Only starting statistic, tomes and level up points count towards qualifying for Divine Might, which adds 2/4/6/8 to every attack's damage for 1 minute for a turn undead attempt. The charisma requirements are very steep: 14, 16, 18 and 20, and the level requirements are also steep (5, 10, 15 and 20). Pure paladins seeking for Divine Might 4 consequently must start with very high base charisma statistics to reach 20 even with the addition of a tome. Drow paladins have a significant advantage in this area. It is important to keep in mind that per point spent, Divine Might gives more damage per point than Strength, until you qualify for the highest DM your level split permits. This is why you will see that every build I link to in this thread, and all the sample builds, feature extremely high base charisma. It is a critical statistic, and making a paladin that starts with Charisma as its highest stat is quite realistic and even likely. However, since Charisma's value declines rapidly after you qualify for the tier of Divine Might you intend to take, its extremely rare to put your level-up points in the statistic.
Paladins (and monks) are click-based classes. They both acquire many abilities with short or instantaneous durations that must be activated frequently during combat to maintain their damage output. If you do not like keeping a variety of abilities with 3-second cooldowns firing during big fights, this is probably not the class for you. A barbarian or ranger has little to do besides position while auto-attacking, but while playing a paladin it can be quite difficult to keep track of the play area and your ability cool-downs at the same time. However, a paladin that doesn't use his short-term buffs and combat abilities is a very poor character, so be warned.
Divine Might: Already covered in the Charisma section, Divine Might is an enhancement that consumes a turn undead attempt to provide a bonus to damage for 1 minute. A higher level paladin will easily have enough turn undeads to power this ability between shrines, and as it is not a spell it doesn't slow you down when used on the run. Divine Might adds more to your damage output in most situations than any other paladin enhancement, and it is important regardless of what role you choose to play.
Divine Favor: Divine Favor is a level 1 paladin (and cleric) spell that provides a +1 luck bonus to hit and damage per 3 caster levels, up to +3/+3 at class level 9. Its duration is 30 seconds + 6 sec/paladin level, so at low levels you will find that it is extremely short. It's rarely worth even bothering with until at least level 6, and you probably won't have the spell points to keep it running regularly until level 12-14. Once you can, though, it's a very valuable buff, and your only buff that increases your to hit as well as your damage output.
Zeal: A level 4 paladin spell, Zeal gives you a 10% chance to double-strike. Prior to July of 2010, Zeal was an attack speed booster instead, and you may see references to it as a speed boost. Information suggesting that the spell is poor or insignificant is badly misleading and should b disregarded. This is a very important buff to maintain any time you're fighting anything. Many paladins take extend spell to improve the mana-efficiency of Zeal, which has the same duration as Divine Favor (30 sec + 6/level). Paying 25 sp for 2:12 or 35 for 4:24 of Zeal should make it clear why, as paladin spell points are not all that great. It is worth noting that the changes to Zeal made it interact even better with smite evils, which can get the double strike effect and go off more than once per use. You also can still get an offhand smite, though these will rarely coincide (you will get all 3 smites 8 in every 100 smite attempts).
Divine Sacrifice: Divine Sacrifice is a clicky-operated ability. It costs 5 hit points and 1 spell point to operate, and has a 3 second cooldown. When activated, Divine Sacrifice will take place on your next auto-attack (or it will do an attack animation if you are not attacking). Using this ability while dual-wielding will cause you to do one with each hand when an offhand attack occurs. Divine Sacrifice adds considerable light damage (5d6/7d6/9d6) to the attack, in addition to increasing it's multiplier on a critical hit by 1. The light damage alone is considerable if the ability is used constantly, and if a weapon with high critical chance is used, so too is the additional critical multiplier. More on weapon selection for paladins later.
Smite Evil and Exalted Smite Enhancements: While frequently the first ability that springs to mind for paladin damage, smite evil is often the least important. The Exalted Smiting enhancements make Smite evil incredibly powerful for burst damage: increasing it's sizable (pal level*3 + 7) bonus damage with improved critical ranges and multipliers can lead to critical hits in excess of 700 damage. However, the enhancements are very expensive (20 of your 80 action points to max out exalted smiting 4) and you have a rather limited number of uses: even a fully specced smiting paladin only has 13 per shrine, and they recharge at the rather slow rate of 1 per 90 seconds. Exalted smiting should not be overlooked, but if you're strapped for action points, it should be the first damage-dealing enhancement you cut out, not the last. It's limited number of uses makes it far less valuable than Sacrifice or Divine Might (which are competing with it for AP) in any fight longer than 45 seconds. Like Divine Sacrifice, dual-wield smiting can trigger a second smite with your offhand weapon with the same chance as your regular offhand attack (ie based on how many two weapon fighting feats you have, up to 80% chance of a 2nd).
As you can see, paladin melee involves managing 3 short-duration buffs and 1-2 clicky abilities, so it will take some practice to do it well. However, it leads to a far more interactive combat than you get out of other classes. Some people will like this, and some won't.