Spend as much time as you can exercising and getting into really good shape before you start. Even if you get into decent shape, the AT will still kick your butt. It’s a different world out there.
Sleep outside and test out your gear as much as possible. A couple weekend overnight hikes would be good to learn, test gear, etc—get used to it, etc----and you’ll probably find out some things you’ll need/want to take from it also (and some things you don’t need). Cook some also like you would do on the trail. Use your gear, test it out.
Get some inputs from Bluebearee, Apple Pie, Bushwhack, and a few other well known and experienced hikers. I’ll trust their knowledge, wisdom, and advice.
Figure out how you’re going to do your money so you will have constant access to some, but not all of it with you all the time. Money orders, travelers checks sent to Post Offices along the way by someone back home is good.
See you out there.
:cheers
Maintain