Ten Lessons Learned in Ten days on the Trail

Me at Neel Gap. 

1. It's as Hard as Advertised
Those who have said the trail is tough are correct. It's often steep, full of ankle turning roots and knee hating rocks. It's possible in a single day that you can worry about hypothermia and heat stroke. You spend all day beating up your body, just to get up the next morning and do it all over again. The uphill climbs seem to go on forever, and the downhill climbs aren't any better, particularly for a hiker with a high center of gravity. It's often not very fun and can really feel like work.
2. It's Something I Can Do
On the other hand, the trail is something I know I can handle. Before I started, I worried about downhills, and if I could get down even one mountain that was rocky or muddy. Having made it up and down many mountains of varying difficulty, I know now it's something within my power. It may kick my butt, and I'm still really slow, but a I've conquered some really nasty peaks with some ugly grades.
3. Don't take the Freeman Trail around Blood Mountain
Coming down Blood Mountain is arguably the toughest part of the AT in Georgia. It's steep, rocky, and packed with hikers. Thus, when Erin and I weren't feeling it as we approached Bird Gap before the climb up Blood Mountain, a bypass sounded like a good idea. Had I seen a warning sign about it's rockiness, I might have reconsidered. About five hours later, after climbing around and over a labyrinth of rocks, roots, and mud we were through. This situation left us frazzled and temporarily uncertain of where we would sleep that night. Sometimes the cure is worse than the disease.
4. You can hike in the rain. And put up a tent in the rain. And sleep in the rain.
"If you can't give in the rain, you can't make it to Maine." This common refrain is accurate, as far as I can tell. Unlike the PCT and CDT, which have hundreds of miles through the deserts of the west, the AT travels through some of the wettest parts of the country. Mud, rain, and thunderstorms are a part of hiking as much as trekking poles and awful hiker stench. It's never fun hiking, sleeping, cooking, or using the privy in the rain. But it can be done. And heck, with some good dry bags you can still sleep in a warm sleeping bag and have a warm meal. Plus, a lot of rain means easy water sources.
5. Night hiking can be terrifying and serene, often at the same time.
For various reasons, most of all because I'm a show hiker, I've had to do a fair amount of night hiking so far. It can be a bit terrifying, especially when trying to go over steep rocky terrain, or deal with rain or snow. However it also has its own beauty as well. Night hiking is often quieter than day hiking, and although the lights in the valley destroy the illusion of true wilderness, they have a character of there own. And very little is more encouraging than the light of a distant for set by your fellow hikers drawing you in to your night's camp.
6. You aren't the only one with the idea to hike the AT.
It's easy when planning your AT hike to think of it as a solitary effort. However, attempting a through hike of the trail is a popular thing these days, and the trail can be quite packed. That doesn't mean there isn't plenty of solitude, but don't expect much at shelters, hostels, and campsites. It's still an uncommon thing to do, but thousands of folks hiking makes it feel less so.
7. If possible, Hike the Approach Trail
It's very easy to avoid the 8 miles of the Approach Trail and still hike the AT. I would suggest sucking it up and doing the pre trail. It gives you a good idea of how the trail works in Georgia and skies you to avoid hiking the same mile up and down for those who don't like repetition. It also give you a chance to hike a portion of the original path of the trail, when it still went to Mount Oglethorpe 
8. If possible, Hike the Amicalola Falls portion the Day Before You Begin
That said, I would recommend doing the first mile or so of the approach trail by itself. This includes the scenic Amicalola Falls and the 604 stairs to the top. By splitting it up you remove the toughest climb of the trail, and gives you a chance to appreciate the "opening ceremonies" and the falls better.
9. Take your zeroes
When you are on the trail, that mileage count can wear heavy on your mind. If you aren't careful, it can crowd out your body's signals, until you are too broken to continue. As point #1 said, this is hard. It takes a toll on your body, your soul, and your mind. You need a day or two off every so often. Towns are great for this, but they can vacuum money. However, if you're on a budget, you can zero at shelters or campsites pretty easily. On the other hand, towns have beer, A/C and fried cheese.
10. DO NOT HIKE THE FREEMAN TRAIL AROUND BLOOD MOUNTAIN!