Yah, its a learning process, learn from experience. You should give a quotation and ask for deposit, don't start any work yet. In the real world nobody going to pay you what you are worth, unless you are lucky and bump into a nice client. Even after so many years, still can get cheated. After awhile you will start to notice the warning signs even before starting the project, so can reject the client earlier before the problem becomes worse. One of the warning signs is.... they want to buy you lunch/dinner, or they start talking to you like you are part of the team/business partner, or they get shocked or react negatively when you tell them your price, or even before starting the project they start scolding you.... anyway, I just want to say, as a freelancer, one of the keys to success is to select your clients carefully.... stick to positive, happy, successful customers...