Ditto the book by Bryson. I enjoyed it immensely.

I'd suggest finding a group to hike with. Sounds like you're already in decent shape if you're hiking now - but can't stress enough the importance of training. Next time you go hiking carry a backpack with weight in it similar to what you'll be bringing - 30-50 pounds. Load it with canned goods or exercise weights.

Go camping at least one weekend before you venture too far away from the trailhead with the plan to bring everything with you that you will need. That is a big concept for new backpackers, the idea that you'll need to bring in *and* bring out every single need. For me beverages have always been the biggest issue!