I have a few!
-Keep some sort of identification on your person AT ALL TIMES!! Sometimes, you just don't know what kind of weird crap you'll get into during a con, so if something happens to you, people know who your are and can get the right help!
-Con money is secret money. Don't start wacing your money around like a rich bastard. 1) people hate that and 2) it's more likely you'll get it stolen. Try your best to keep most of it out of sit and only take it out when buying something. Also, keep it on your person AAT!! Again, less chance for it to get stolen.
-I know this has been said before, but it sucks when the guy next to you in line smells like B.O... SHOWER Regularly and USE DEODORANT!!
-Make friends! Sadly, at my past few cons, I didn't socialize and meet a soul! Try your best to be social! People at cons are nice and are into the same things you are!
-Be nice to staff! A lot of them have to deal with the con bastards and douchebags for most of their shift,so they're stressed out! Just follow the rules, be considerate, and give them a hug! They know they want one, and they really appreciate it :3
-Don't play your music
too loud. Some people may not like the song and find it annoying. Try to remember other people are trying to have a good time. If you want to play music, try to keep it at a volume only you and your friends can hear
-If you find Waldo, TELL ME. I WANT TO FIND WALDO!!
-Like Mudflap brilliantly said in Transformers 2, Revenge of the Fallen, "MEAN ROBOTS SUCK". Same applies to people. Ignore the suckish people being douche bags and are trying to ruin everyone's con time
-Try not to lose the game to much. I've already lost 5, now 6 times today. Think about how bad it is at a cons?
-Ask for photos! You won't get a good shot just by swinging past and taking a stalker picture anyways...