Many professions require payment in advance particularly for small jobs, if that is your policy then stick to your guns – see what happens. The more rules you have in place early the more they will respect you because the assumption is you must be good. A brain surgeon tells you what to do because he knows more about the topic than you do. Same with you – you are the expert and the leader when it comes to the process. They are the boss when it comes to ‘go’ or ‘no go’