My advice:
Some research and planning is always good, but don't over-plan or convince yourself that you'll only set-off on the trip once you know everything there is to know; you'll never end-up going. Most tourers' first trips contained numerous small mistakes which were learnt from.
Take enough (and the right amount of stuff) to eat, repair your bike, wear etc. You'll learn more about what works/feels right by doing than by reading. Learn and read as much as you can, then set a date and GO!
I always feel the hardest part of the trip is the first five minutes. Actually starting the tour. Thinking is easy. Riding may/may not be easy. But that first step is the most important, and the most difficult
Goodluck.