Each guild is a little different - some do more charity work, some have gobs of classes, some are "stitch & bitch" groups .
My suggestion for any group/organization you join is to VOLUNTEER for something right away. People complain that clubs/guilds/groups are cliquish(?) but that's generally because they show up for a meeting, never volunteer, never speak up, etc. When you want to be part of a group - put yourself out there -- ask what you can do.