Traveling around USA with my friend who is from the UK in 2 years, any advice/tips?

I have lived in america for all my life and only 1 state we are planning to visit is somewhere i know well, and the other (which he will be landing in) i have only lived in for 2 years or so. (we are visiting around 30 states within a month, maybe a bit longer), also there may or may not be a few friends that we pick up along the way but it hasn't been decided for sure yet. I have never had such a big travel so i would just appreciate some tips and also maybe some ideas of what to do? But i'd mainly appreciate some advice, thanks!