My only advice would be to not plan too much (though some places will obviously require meticulous planning). Have a broad geographic idea where you want to go and let your travels happen. Some of the best places I have been weren't places that I had initially thought I wanted to check out.

I had initially planned an 8 month RTW trip that took me over 5 years. I had a RTW ticket that I ended up throwing 3/4 away and just used one way flights/train/bus/bicycle/feet from there.

Have an awesome time.