I had braces for a little over two years. Got them removed this last August.
You
will be sore. It's totally bearable, though, and you'll get used to the pain within a few days. Until then, take an ibuprofen (or two, depending on how uncomfortable it is) every few hours if you need it. You should also take one before getting your braces tightened. Trust me, it helps a lot. Also, eat softer foods until you feel ready to go back to a normal diet.
Speaking of such, I'm sure you got the whole lecture about not chewing gum and all that. B.S. I chewed gum all the time with my braces (in addition to eating popcorn, peanuts, etc.), and I never had any problems. Just don't chew any gum for a day before you go in (same with eating popcorn) and they'll never know. Heck, I was at the orthodontist once when someone else was getting their braces on and the ortho was telling the person she was working on what a good example I was. XD
One thing I had problems with occasionally was canker sores caused by the rubbing of the brackets against my mouth. If you feel any bracket rubbing against your mouth, put a little ball of wax on it. You should've gotten some from your orthodontist, but if not, or you got some really flaxty silicone-based stuff that's impossible to use like I did, go to the drug store and pick up a pack. It helps so much.
Finally, when you get your braces tightened, always make sure you don't have any wires poking you, and if you do, let them know before you leave so they can take care of it. Two extra minutes to alleviate a month of discomfort is totally worth it. Also, like Jewjo said, wear your rubber bands if you get them, and make sure you know where they're supposed to go. I usually didn't wear mine for a day or so after getting worked on since my teeth would be too sore for that, but after that, I wore them as I was supposed to. No problems.
EDIT: Yes, wear your retainer like you're supposed to when you get them off. I speak from experience. Besides, if you wear it like you're supposed to, you don't get all lispy-sounding from it not fitting right. However, I usually leave it out for the day if I'm going to a water park or somewhere it could easily get lost forever.