Pack light of course.
Clothes: items should be able to be used in 3 different outfits or it's extra weight.
Laundry: pack a small baggie of dry detergent, you can either hand wash undies/socks or use the detergent in laundry facilities, a clothes line is nice to have if you really want to avoid laundromats, many airbnbs will have something for you tho
Keep snacks along for the travel times, bars, nuts, etc
Bring a water bottle
When in California, visit trader joe's for precooked foods if you have a fridge, a salad, chicken breasts, hard boiled peeled eggs, etc. They have stuff if you want to avoid fast food and expensive eating out. This works great if all you have is a fridge and microwave.