If you are wearing a wig, wear a wig cap~ Even if your hair is short, the wig cap still helps to keep it in place and it keeps the wig clean. ;D
Brush your wig with a comb and do not brush it when wet. I know it's easier to brush knots out when hair is wet, but we grow our hair back and wigs don't. ;A;
is a nice tutorial on how to wash wigs.
If styling a wig, use hair spray or gel that doesn't have alcohol in it.
When attending a con, bring a water bottle and some snacks! But, make sure you eat some real food too, if you are at the con for a long time. ^^
You'll also want to bring a small bag with you to put your snacks, water, camera, and phone in. Just make sure you keep track of it when you put it on the floor to have your picture taken.
If you are wearing make-up, you might want to bring some extra with you in case you are in need of some re-touching.