Wear long pants to protect your legs from hot seats and other people's sweat. I suggest long flared yoga pants that drag on the ground. Wear a tank top and a good supportive bra. Hair in a ponytail. No huge hoop earrings. Don't bother with makeup but make sure your nails are polished. You'll loose flip flops so wear sneakers or sandals that strap onto your feet. Wear sunscreen and drink water. Have fun.
When I went to Six Flags, I wore shorts and a bunch of hoodies. But, you should do the opposite, wear a loose tanktop, some skinny jeans, and some Keds or tennis shoes. Hope this helped!