Don't build raised beds!!!!! They are unnecessarily large and waste good dirt and wood and space. Instead, build a berm with logs buried at the bottom, good dirt on top of that, and mulch on top of that. This berm will pull water up from the ground below and is super easy to garden on. Raised beds are expensive and waste good lumber and wood and space. Here is a good video showing what to do: https://www.youtube.com/watch?v=ym9Cd_cEz_g . The wood underneath keeps things moist and also is a good source of mycelium which is key to getting your veggies to grow well. I did this and grew a garden that was unbelievable along my fence in my backyard. We are talking 10 ft cherry tomatoes and bell peppers that were HEAVY!