Some people want different things from a guild. Here is my opinion of what you should not expect:
1. The guild does not make the game fun. If AO is not fun for you anymore, there is very little that anyone can do about it.
2. Don't expect a lot of free stuff, especially if you are new to the guild.
3. Events are a part of guilds, but someone needs to organize them. If you have an idea for a fun event, then organize it, the guild will help you, but don't expect someone else to do everything.
4. Most problems with a guild have solutions, but they require work, the best person to do this work is yourself. No events? Organize one. No one to team with? Recruit people of your level into the guild. Someone is doing something you don't like? Discuss it with them, in /tells. Don't just say "I don't want to get into the details, but the reason I am leaving is because of Mr. X". Not very organized in PvP, or Dungeon raids? Be the organizer!
5. Don't expect someone that posts loot to wait around forever for you to show up.
6. Don't expect the undivided attention of a guildmate. I usually start my /tells with "Are you busy?"
There is a relationship between you and your guild, and, like most relationships, what you get out of it depends on how much you put into it.