it is really simple.......learn how to say NO........then they will stop coming...if they dont get what they want from you they wont bother asking you. if you find it impossible to say no, because we all fear people not liking us, at least get some of your needs met in the process. have them sit down and chat with you before you give them an answer. let them make you dinner, clean the bathroom, get something for what you are giving to them so you dont feel so used.