Diet is everything: eat breakfast and drink water. I'm not kidding. Eggs, bacon, hash browns, sausage, orange juice, etc. If you don't eat a good breakfast, you'll be stuck with fast food or convenience store food when you are hungry. After two or three weeks of that, you'll be 20lbs heavier and really sick of burgers and fries. I have found that by eating a large breakfast, I can go with the flow- if it's a busted day, I can graze, but if it's an active chase day, I can go the whole rest of the day without eating.
Water- stay hydrated at all costs.
On good chase days you will not have time for a nice dinner- on fair weather days, get a salad. Even if you hate vegetables, you will start to crave them after a few weeks on the road.
Vitamin C/Zinc- if you chase with other people, and will be in a vehicle with them for a billion hours a day, and your immune system isn't ready for it, you'll spend the day in the hotel room instead of in the storms.
I also bring an electric skillet. Why? You can cook a million things in one. I have made stirfrys, poached fish, cooked pasta, etc. all from an electric skillet. It takes forever, and some hotels won't allow it- but some towns close up shop at 7PM, and there are zero food options. If you have an electric skillet, this is no concern to you.