Do unto others as you wish they do unto you...
This is the best way I find in life. It does leave you open and susceptible to being used and abused, but if in your heart you know you are doing the right thing, then for all the users you meet, the abusers that take and the people that take advantage of generosity.... can take, take, take.... but it will never let you down as a sound human being , walking the right path, sticking to the right thing.
(i'm not saying it won't annoy you in the process, because it sure will)
True, it's much more than just annoying to cross paths with such people, downright depressing but you can't let those factors weigh you down and stop you from doing the best you can.