I would just like to reiterate the importance of a contract. You won’t realize how important they are until you are super happy that you have one (or super depressed because you didn’t).
Both parties will always be going into a project with the best intentions, but sometimes things go sour – it’s inevitable that this will happen at some point. Just recently I had a client argue with deliverables and try to go back on things that were already approved. Luckily I had a contract in place that gave me the safety of not losing my deposit and we went our separate ways (although one of us was a lot calmer than the other!).