Don't sweat the small stuff. That's it really. No need to faff around making Christmas pudding, cake, mince pies (and your own mincemeat to go in them), Yule log, 3 sorts of stuffing, sprouts with chestnuts and pancetta, yadayada. If you want them, buy them ready-made. Probably cheaper anyway.
Do away with that horrid elf on a shelf or the Xmas Eve box. Just get basic advent calendars instead.
I long ago delegated the writing of Christmas cards to DH. He is also 100% in charge of all drinks over the festive period.
Don't buy Christmas chocolates too soon. You will eat them. Leave them till December.
You do not need every condiment and variety of pickle under the sun. Nor do you need 17 different types of cheese.
If you have children, they do not need entertaining with Christmas-themed activities for every minute of every day between the moment they finish school and the morning of the 25th. A (free) carol concert and maybe a Christmas tree festival in the local church (also free) is fine. Santa at the local garden centre is just as good as the one that costs ten times as much at the Winter Wonderland. The rest of the time they can get busy with crafts, or watch endless Christmassy films.