My way to reduce holiday stress comes in two parts. First of all I "do" Thanksgiving dinner, then throw a big Christmas bash the first or second Sunday afternoon in December. When we first moved here (8 or so years ago), we formed friendships that work well for us. We do Thanksgiving and that early holiday party, other friends do other holiday dinners or parties. By the tenth of December, I'm pretty much done.
Then, about ten years ago I pretty much gave up buying presents. Yup. We took the commercial right out of Christmas. I don't much like to shop, period, and the first time I started hearing Christmas before Halloween, that was that.
So now the shopping I do is for our local food bank and anonomous gifts for needy families. My husband, my sibs, nieces, nephews ... I just don't. Not ba humbug, just that I was spending money on stuff no one really wanted, just so that they'd have some box under the tree. The gifts everyone really wanted were well over my budget. None of the kids actually liked to read (books would have been my gift of choice). Having to find just the right gift for someone I hardly know any more, and who as far as I can see are priveledged enough ended the year I found myself in a trailer (by choice, not because of poverty, just for love of travel) next to a family that wasn't sending their kids to school because they couldn't afford to buy them clothes. We stopped buying for each other and for family, and started taking an annual trip to Wal-Mart for these needy families. You cannot imagine the release it was to not be trying to find the perfect gift for the person who has everything they want already.
I minimized decorating, which works well when you live in an antique home, help where I can, but gave up on buying stuff for people who don't want or need it. The stress, voila! went away! I now have maybe one or two hours of stress between Thanksgiving (when I try to keep the table at a manageable 6-8 people) and my Christmas party (where the rule of 40 applies! It is a family joke. I invite 20, 40 show up. I invite 80, 40 show up). Then I hit a discount store and drop my buys at a local bar. I get someone with all-wheel drive to help deliver the food bank items that I charge for "party admission". By mid December I'm done for the year and can truly enjoy my holidays.