I think good puncture resistant tires are the 1st thing to get. I believe Schalbe Marathons are highly recommended. I have the Panaracer RiBMo's on my touring bike.

After that I would do a test ride on your route with things you might be carrying. You don't need to go all the way and back, just 1/2 way should work.

First it will allow you to notice if you are fit enough. Secondly it will give you a rough estimate on time. Third it will tell you what the road/travel conditions will be like. Fourth you will have a greater understanding on your body, and your contact points on the bike (in case you need to change or add things like saddle, bar wrap, stem height, etc.).