The VATSIM idea is good, but be prepared to deal with a bunch of 13-14 year olds who have incorrect phraseology fulfilling their ATC fantasies. You don't want to learn bad habits, but hopefully it will get you in the swing of things. Also, don't be surprised if the VATSIM folks aren't familiar with VFR procedures as they're 90%+ handling IFR jets I think.

You may want to consider taking some tower tours to meet the controllers in person and chat with them. Maybe seeing them in person, talking to them, learning what they like and what they don't like could be useful for you.