Make A List
Make a list of every person you need to buy a present for. Carry it with you wherever you go, and cross names off as you buy.
Set a Budget
Set a budget and stick to it. This way you won't get carried away.
Christmas Cards One Day At A Time
Write a little very day until around the 14th. Then you can mail out all of your cards at once.
Wrap As You Buy
Wrap your presents the night you get them home to avoid feeling overwhelmed by the task of wrapping all of your presents at once.
Make sure you account for shipping time, but shopping online is a great way to avoid the crowds. And the malls. Ugh.
Buy A Real Tree
This might not be for everyone, but the smell of pine in my house always calms me down and makes me feel festive. Maybe if you don't want to go all out and get a tree, you can buy a wreath. We don't have room for a tree this year, so I plan on getting a wreath for our living room.
You don't have to do everything. Learn to diplomatically say no.
Nothing like unwrapping the presents on Christmas Day and finding out you won't be able to use them until you can get to a store to buy batteries!
Watch Christmas Movies
My personal favorite is It's A Wonderful Life. My grandmother and I used to watch it together while we wrapped presents. I like seeing it at the Brattle Theatre in Harvard Square, which has an old timey stage with curtains and everything. It's magical.
Take a Day Off
Once you've done all the shopping, wrapping and cards, take some time to unwind and do nothing.
Even if everything doesn't get done, the holidays should be about this above everything.