Say what you mean. Sometimes it feels like the best thing to do is say “Maybe” or “I’ll think about it” when what you mean is “No.” It may seem like the polite and easy way of saying “No,” but it leaves the door open to getting to “Yes.” So if you really mean you want to think about it, say “I’ll think about it.” But if you really mean “No, I really don’t have time/can’t/don’t want to,” then politely say “No” the first time, and be done with it. It gets it off of your plate, and allows the person asking to move on to another person.