I would also recommend the APA's guide book. There is also an online companion that is searchable, but is only accessible with a paid subscription: http://psycinfo.apa.org/gradstudy/?action=info. Your school may have already purchased a subscription, mine has one that all Psych students can use. Check with your academic affairs office.
It's really great that you're starting early! The best advice I can give you is to get as much research experience as possible, and talk to your professors about programs they would recommend.