Definately show up early to watch practice and roam the pits before the crowds. Some of your best pictures can be taken during practice. Bring a cooler of food and drinks to tailgate. Food at the stadium is expensive (think football). Since I flew in, I was taveling light. I taught the son how to make a college cooler, beer in the trash can from the room, covered with ice from the ice machine. Saved about $7 a beer. A back pack is helpful to carry camera, binoculars, water, stickers, ect... Definately bring earplugs and a hand towel (to wipe your seat) and don't wear white, lol. That dust gets everywhere.
I went to the Dallas SX last year. I'm from MD, son lives with mom in TX. Did a dry run to the stadium the evening before so Dad wouldn't get lost. We were able to walk the pits and get a few good pics. We saw RC's, CR's, JBS's and KW's bikes. When we got to Travis's pit I started talking to his Dad. He invited us behind the gate and let Stephen sit on his bike. You can say what you want about that kid, but they are a very gracious team. We didn't want to overstay our welcome so we shook hands and went on our way.
We had a great time. Good luck