Tips on packing:
If you cosplay: You will be in cosplay constantly. Trust me. You won't need 2-3 changes of normal clothes if you're cosplaying. It'll be unused and just take up space in your bags. Unless you intend to go elsewhere and do something where you want to dress normally (what's the fun in that), you should only need sleep clothes, clothes to wear on the way there, and clothes to wear on the way home.
Cosplay repair kit is good idea.
Camera and extra batteries.
Music and such -- sometimes to make travel more enjoyable, sometimes to be used in the karaoke room.
mini first aid kit: headache medicine, bandaids. Blisters and headaches can happen, and it's better to have than not have.
Person neccessities: Remeber proper hygiene! At home you might be able to go a couple days without a shower, but this is a bad idea at cons. Take a shower at least ONCE during the middle of the con, and please have a shower the night before heading to a con. With all the people around, do not take keeping the air fresh forgranted. Shampoo, conditioner, toothpaste, tooth brush, body soap, etc. As well as any other supplies you might need be it for styling hair for cosplay or taking off makeup.
Also an extra bag is always a good idea. You never know what you'll end up buying at a con, so you better have something to pack it into. If you're bags are stuffed on the way there, odds are they'll be stuffed on the way home, and what are you going to do about all those goodies you just got? (Unless you packed alot and food and ate it all by the time the con ended.)
More about food: Don't do what my friends and I did--pack more food than we could reasonably eat. It's good to be prepared, but if everyone in the group brings more food than they can eat themselves, you might have over done it. Also if you're with friends, do not be afraid to designate something as "Mine only!" to insure that you have enough food for yourself. (I do this with my slimjims and hot cheetos. they are MY emergency food rations. Mine! All mine!)
Unpacking: either keep your stuff in teh luggage, or you can claim a drawer in the hotel room.
I personally claim one drawer as the 'food drawer' for all the food that anime can share. It's better than keeping everything on the tables and such--neater too.
More on hotel: keep the do not disturb sign up all during con if you don't want to risk your room getting clean and something inadverdantly coming up missing due to cleaning crew not knowing that it wasn't trash. (this goes back to the using a drawer comment.)
Use cell phones if you can instead of the hotel room phone -- cheaper.
okay, I skimmed what was said on the first page, so I hope this isn't repeat stuff.