All you really need to prepare for is you next resupply of each of your consumable/'wearoutable'. - this applies for the entire trail and all you need to know, the rest of the post is just extra.
Now to this you will learn as you go to add in things like restaurant stops, minor resupplies, trail magic, hiker boxes, ect.
Also additionally though it is fine without these I would recommend:
1 - Especially for NoBo, mail your resupply to Fontana Dam as it is expensive and limited to buy there (SoBo's not that effected as NOC is soon after)
2 - Consider a food drop in the middle of the 100 mile wilderness (was $20 at LakeShore house for me), makes life more pleasant and the sun shine more
3 - Know about the permit in the smokies, but that can be done on the trail, plenty of opportunity to pay and print it.