try out all the anime cliches and see if they really do work...like every character has the ability to jump higher than normal world physics suggest....running with bread in your mouth when late....smiling with my eyes closed and still look cute not stupid etc.
I think I'd probably want to go to a slice of life anime and just be able to relax there and talk to the characters that you get to see throughout the anime and just enjoy life there. Sure depending on the anime in question crazy things could end up happening but I think it would be really fun. I'd probably try to get a girlfriend there as well once they are 18 since usually I don't really have any luck finding a woman who likes me and enjoys similar things that I do (video games, anime, tennis, golf, talking and having fun, talking to friends (though that'd be difficult unless there is still some way to communicate back to earth from the anime world (or my friends came with me to the same world)), not drinking/smoking/using drugs, being a Christian or open to becoming a Christian, and probably some other minor things I can't think of at the moment). Also I would wonder for this if you'd be in whatever anime you choose forever or if there's a gateway or something to leave to go back/ to another anime world. You would have to be careful about some anime worlds though as not all of them are safe enough to visit. (For instance the Pokemon world would be extremely dangerous unless you were a main character since they can't ever die (though to be fair there were some close calls for Ash throughout)). That's why I think slice of life anime would probably be the safest overall unless it's a crazy slice of life like Nichijou. I think it would be cool if there was some kind of portal that lets you travel there and back though because then you might even possibly be able to bring the anime character you like back to Earth and that could also be interesting. You would almost definitely need to learn Japanese though otherwise even if you got there you wouldn't be able to talk to them or understand them at all. There really are a lot of things that go into this.