Most experienced freelancers will tell you that a clear written agreement at the start saves a lot of pain later. When the scope, the price, the revision limit, and the deadline are all written down and agreed on, there is much less room for a client to say they expected something different. It does not mean disputes never happen, but it gives you something solid to point to when they do. Do you think new freelancers lose money more often simply because they skip this step?