Sally, what are you going to do with your username when you change bikes sometime down the line?
As for planning, I would begin with two tools ... (1) maps and the (2) internet.
(1) Take a big map of a whole continent or of the world ... plan out a rough route. As you get more certain about the route you want, then buy smaller, more detailed maps to fine tune it.
(2) Google Earth and Panoramio ... for me these are great planning tools. Panoramio allows you to see pictures that are geotagged ... a map that has links to pictures of sights of interest in certain regions. When you see scenery or places you really want to visit, make a note of it, and plan your route through there.
Once you have your dream route in your head, you can begin planning what bike and preparation is suitable for your planned route, and what paperwork you will need.
But for me, every trip begins with dreaming up the route. Sort out a route and progress from there.