Waterproof shoes are always the answer. You can spray an existing pair with a good waterproofing spray and they'll repel water for at least a year.

I'd highly recommend you spray down your tent with this stuff to add a layer of waterproofing. The difference it makes is incredible, water just beads right off. My $50 tent with silicone on it repels water better than my friend's $600 tent. I've made it through some SERIOUS rainstorms this year and never had water infiltrate my tent.

If you're short on space (either crammed in a car or flying), I'd also recommend grabbing a couple of these to add a little bit of shade to your tent. It's not as good as a canopy, but it's way better than nothing. I clip mine right over top of my tent with some binder clips. They're more expensive than the $1 mylar emergency blankets, but they're infinitely better since they don't crinkle or tear, they fold up nicely, and they are only reflective on one side so they reflect heat and light out but not back in. I've used these for super hot festival from Forest, to Burning Man, to Envision in Costa Rica and (in combination with a fan) it's kept my tent cool enough to sleep through the day - it makes a HUGE difference.

Speaking of sleeping through the day, make sure you grab yourself some foam earplugs and an eyemask - I'm not going to link because there are 500 options and you can get them at the dollar store. I can sleep like a baby through anything with those two things.