I would recommend taking:
A binder. You can put any good stuff you get in it, as well as take any of your other trades, so that you can trade with other people.
Sleeves, so that the cards you use in the tournament don't get damaged/scratched up.
A deck box, anything works. Some people use tins, which is fine.
Dice/Damage Counters, even though a lot of the time, your opponent will have them, it's always good to be prepared.
But to be honest, that's all i can really think of.