In the last two weeks I have received guild invites by virtual junk mail and been asked daily by other players if I wanted to join a guild. It was happening so often that I looked to see if my ignore guild invites flag was still set and it was.
These methods seem to be an inefficient way of recruiting new guild members.
An easy way to gather guildless newcomers in one place would be as part of a group doing certain quests on normal difficulty. The Pit, Xorian Cypher, and Invaders, are all quests that are better with groups, even on normal. Running Tempest's Spine on normal should attract them too. Few newcomers can finish the free to play raid by themselves.
Normal level LFMs should be a more efficient way of finding guildless players that may want to join a guild then asking every one. Just saying.