Many guilds out there have their recruitment posts up on both the realm forums and the global recruitment forums. One of the big keys to a recruitment post is to keep it up on the top of the forums so everyone sees it, and sees it before any other posts. This means that you and your guildies have to bump the post to the top of the list, and bump it quite often.
The global recruitment forums recently underwent an upgrade, where the forums were split into Alliance and Horde factions. This has helped a bit with the number of posts per day, and has thus lessened the number of required bumps a recruitment posts needs to keep it on the front page.
However, you still have to bump it quite a bit.