honestly i think its fun that you mention GaiaOnline, because i use SL for just about the same thing (which is predominantly dress-up). hanging out with people is fun of course! id find groups with your interests, that's usually how im able to meet and talk to people outside of sitting at a social place and chatting.
it can be pretty hard to socialize, a lot of people keep to closed group chats or dms but dont lose hope! i would put some of your interests in your bio, honestly i find that works best as despite the fact that i almost never initiate conversations with people if i see a game or anime i like ill end up trying to chat with them anyways...
the learning curve in SL is....really, really steep. since everything is practically user-generated it can be really hard to learn the ropes, but me and my friend wrote a guide once for our own friends so if you have any questions id hopefully be able to answer them!