I am developing for a long time (over 11 years), and for myself, I determined the rules that build cooperation with my clients. 1) The quality of the product - the key to future relations. I try to work on each project so that the client is satisfied and decided to have their business objectives. 2) Development time - should not be exceeded. Client as his business often can not wait, so missed deadlines - often fatal. I put the timing so that the deadlines were not created.