1. Dodge first, then digest.

"Never answer in the moment, under pressure," says author Patti Breitman. Try "Let me get back to you." This gives you time to weigh your options and compose yourself before answering.

2. Don't fall for flattery.

If someone makes an appeal to your vanity, "you might not notice that it is the wrong time or the wrong assignment for you," says author Duke Robinson.

3. Is this in your best interests?

Ask yourself if the person who's asking will ever return the favor.

4. Give yourself credit for being generous most of the time.

Don't beat yourself up for the one time you say no when you've said yes so many times before, says Breitman.