I was due on Christmas Day, so DH and I decided we were not travelling 2.5 hours "down the road" to our parents houses, but staying within reach of hospital. So for the 1st and last time, I had dinner in my DGPs house 20 minutes away (any other time we stay "up", there has been so much guilt tripping that we have done our own turkey dinner thing and just visited extended family during the day).
I had a few things bought, just in case a stocking was needed for a new born. A "Baby's 1st Christmas" bib and a Babygro. A tiny pot of sudocreme and tiny tub of Vaseline for the changing bag. A rattle. (Turned out, she arrived very early the next morning instead, so we used them all without them going in a stocking!! 
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This year, traditions won't be so hard to stop, if you start them - but think carefully about what ones you would like or not and how they could work going forward a few years. "Elf on the (bl**dy) shelf" is great for mischief and mayhem for 1 year, but can be more tricky to find new ideas year in and year out. Lots of people love Panto but not everyone does. Lots of people love baking, but again not everyone does.
By the time we had a 1st Christmas, DD was almost a year old. But a few things we did which stuck were:
Christmas Eve Hamper (new pjs etc - see other posts of mine for details) which comes out after dinner for a relaxed bedtime routine. (DD is now 14 and helps acquire parts, but insists on it still appearing).
Advent calendar - but not always chocolate in the pockets - ideas of things to do that day, crafty activities, trail of clues around the house to find a small toy/surprise, free printables from the internet (colouring or activity sheets) rolled up etc. Her DGM made the advent calendar.
We like reading anyway, so I got a few books which were more seasonal (some Christmas, some winter) and DVDs of seasonal cartoons/movies etc - these are stored away most of the year and come out in early December until the tree is packed away in early January. It has been added to, and some have been donated onwards to younger DNieces and DNephews as DD grew out of some. But great to have both bedtime reading, and some for encouraging reading and explaining pictures etc in daytime too.
DD also has a collection of Christmas cookie books.....fairly well used. Her very first Christmas, she was able to control her hands enough (with assistance) to mix eggs with a fork, gently stir together flour and spices, and "cut out" cookies with cutters. Initial years meant her cut-outs were kept strictly for DH and I to eat, but she got better. And it meant that she always had a hand (literally!) in making cookies to share in creche or in school.
I also, from early on, started a tradition of bringing DD to town to do her own Christmas shopping. Like the present for Daddy, her DGPs, as she got older it included some DCousins etc too. I would try hard to not have any other shopping to do that day - collect her from creche or school, do the shopping together (building her up over the years to decide what to buy and giving her the money to do the transaction herself), and then stop at both the "Live Crib" outside the Lord Mayor's House and in a coffee shop for hot chocolate and a bun/sandwich, so we could watch others and see the Christmas lights.
Ooh lights - nowadays it's more just drive around as we are out and about doing jobs anyway, but when DD was small, I would try to find what houses were lit up around and plot a route to enjoy them - often picking these ways to get home from creche etc, but also sometimes putting her into PJs after dinner and doing a drive after dark to enjoy the different lights people had done on their houses locally.
Many DCs don't like Santa so while a photo is lovely, and even if your local Santa is great, that photo may be of a crying baby - so don't be upset if you try and that happens.
We also like a simple dinner on Christmas Eve - mostly cold items (sometimes a few sausage rolls or other "party food" that needs no prep), laid out on the table for everyone to decide what they want themselves.
We do a turkey dinner, because we DO like it and rarely eat big roasts - but with a few nice veg, proper roasties and stuffing, but not tonnes of trimmings. We often have some M&S party food while we are organising that and opening presents in the afternoon, instead of a proper starter, and often dessert is hours later. We have actually talked about doing something different this year, if we are in our own house - but something equally nice and special as a meal we will all enjoy. We tend to do a lot of prep work on 24th (peeling veg and potatoes, making stuffing, etc) so it is mostly putting things in and out of the oven on 25th in a relaxed way.
Because of DD's birthday, we have a tradition of being "at home" on the afternoon of 26th to all neighbours, friends and family who are free to drop in. Some years we've had loads call, others just a few. But we make it very easy - sharing bags of crisps, lots of M&S party food and some turkey sandwiches, a large pot of mulled wine, some beer chilled for non-wine drinkers and plenty of non-alcoholic drinks for adults and children alike.