You have already made the first preperations, you have made up your mind on where to go!! Don't be surprised if that changes, it can and quickly
After that, hmmm, i would reserch the places your going, languages, customs, must sees, things to avoid, transportation ( trains, buses, planes) that kinda stuff.
The next thing I would do is start collecting gear...If you start to buy stuff right before your trip, things can get VERY expencive, but if you start getting things well in advance of you adventure then it doesn't hit the pocket book as hard.
Just a couple "starting off" tips :D