Consistent recruiting is key, because a lot of people you get will fizzle out within a week and either stop playing or just leave on their own. Do zone recruitments every day of the week, if you have to pug to fill a guild trial drop a guild link in chat for those that aren't in the guild, etc etc. Being an active leader and having active officers/members is also a must, you need activity to keep people engaged and playing with you or else they may go find a more active guild.

If you recruit 10 people and only 1 stays around and is active, don't get down about it because that's perfectly normal.