90 Blood Elf Warlock
This is something I recommend for everyone.
Get some Halls Defense or some Airborne. While the convention hall is well air conditioned, there are a lot of people in the same building, and all that body heat being cooled by the AC makes it rather humid. Humidity is the devil when it comes to germs! And with that many people in the Hall touching the merchandise, the keyboards, sharing chairs and air... germs spread fast. Pop your halls like candy and make use of the hand sanitizer stations posted around the hall.
I learned this the hard way last year and had to call out sick from work because I had no voice at all and felt like I was dying. Con plague is the worst.
EDIT: Also, DO for the BO! Always pack deodorant. Don't be that one nerd.
EDIT 2: To help answer your other questions,
1. Check out the program before the convention starts so you can get an idea of what you want to see. Last year they handed out loot cards so we got our in game stuffs, but it also came with a virtual ticket so you can catch up on anything you missed. Remember, what ever you do miss, you can always see on youtube later!
2. Yes, you can come and go as often as you'd like so long as you wear your badge. Don't lose it! I taped my opening closed after I put my badge in it's sleeve so it wouldn't fall out.
3. That depends on how much you usually spend on merchandise in general... I don't tend to buy things, really, unless it's limited edition so I won't carry more than $200ish on me. There are ATMs, though, if you need to pull more cash, but I believe they accept plastic as well. Food is expensive around the place, but there are plenty of fast food in walking distance from the convention center.
4. Lots of people go by themselves! Myself included last year and this year. You'll make lots of friends, especially if you go in costume because people will stop you to ask questions and/or take pictures, but there's always the after parties in the hotel lobbies. Hilton is usually more packed, but everyone goes back and forth between the parties.
Edited by Pai on 8/22/2014 12:04 PM PDT