1. don't visit those relatives you dislike. you save petrol and the environment and your sanity in one decision

2. wrap presents in old newspaper (Stonehead mentioned this one, and I like it so much we are going to do it this year)
3. save old paper from other people for next year.
4. make presents for those you can, rather than buying them tat they dont want. or agree to give less presents. or make wishlists of things you actually want.
5. do all the cooking yourself.