I ask because one of my players wants to me to intergrate Arcane Schools (specifically guilds) into our game so he can benefit from them. Thing is he's the only arcane guy in the group. most of the others are martial and divine and I rather integrate a rule into the game that benefits everyone instead of just one player. So my question is if there's guild-like rules that benefit all types of players or am I better off trying to homebrew something?
Casters don't need additional benefits. If he wants to benefit in the sense that he can role play coming from a school, or have a place to sleep thats fine. But don't let him purchase anything more cheaply or anything to that extent.
Also, there are guilds of every sort of thing you could reasonably imagine. Fighter's guilds (no, not exclusive to fighter class), Thieves Guild, Mage's Guild, Assassin's guild, Druid Circls, Temples, so forth and so on.
The homebrew rules are simple, guilds exist, you can go there to "learn", you don't get any sort of monetary or other benefit as that isn't fair and very likely to be unbalanced.
Guilds are part of the game rules. I think the Game Mastery Guide even lists "starting a guild" as something you can do in your downtime. In addition to what Claxon mentions, there are also many professional and artisan guilds.
I believe you're thinking of the Downtime Rules from Ultimate Campaign. But the benefits aren't really character specific benefits, and it's really only if the GM (Torke) wants to use these optional rules. Again, the benefits aren't really character specific benefits, and these rules assume you're in charge of the guild having created it, not just a rank and file member.