You will be asked if you want to team up and hunt by many high-level players as soon as you get to the mainland. They will heal you, train you, level you, give you stuff, and then ask you to join their guild, heh.
I went off and started my own guild, anyway, though. I just randomly ask people who are not in guilds if they want to join
so far, I stole one person from another guild, recruited my girlfriend, and found two newbies who joined just because I asked if they wanted to. Only one person I asked declined.
I am generally against people who team up with you just to get you to join their guild, but, truthfully, the only way to decide if you like a guild or not is to decide if you like the members or not. Spend a few days pretending you are a member, and hunt/train with their members, and see how many are around your level, etc.
I do not know much about other guilds, though, but just use your best judgment.
Syd, leader of Fyre.