1. Don't spread yourself too thin
There will be many celebrations and parties going on during the holidays. So it will be hard to commit to every party. Whether your families live in the same or different city, there may come a time when holiday parties collide. Or perhaps you and your partner have various holiday parties to attend throughout the weeks. When this happens, high stress can set in when you try to accommodate families, friends, or co-workers. Since you can't be in two places at once, you may try to juggle your time to make it to every party. This will probably cause more stress than be helpful. So figure out which parties are priority for both of you and if they collide with each other, find a way to compromise. It's likely that you both will give up something before you can figure out a workable solution, but this beats spending the holiday separately or stressed out.
2. Don't sweat the small stuff
If your partner doesn't dress to impress or doesn't get you the gift you've been hinting him/her to get you, don't sweat it. The holidays probably mean something different for them, perhaps they aren't used to partying during the holidays, or maybe they are just less festive than you are. The list goes on. There are countless reasons why your partner may not "do" the holidays like you do, but it shouldn't take away from what's most important. So figure out what is most important to you both and focus on that. You might find that it's less important to get the "perfect" gift or look like the "perfect" couple.
3. Expect the unexpected
You've got to be flexible during the holidays. Things may not go as planned and issues that have been suppressed might be reignited when people who are usually separate are put together in the same room. Expect uninvited guests to show up to parties or family members who call minutes before dropping by. Whatever the case may be, flexibility will allow you to sway with the motions rather than break under the pressure. There's already enough stress as it is.
4. Create your own traditions
Sharing the traditions from each of your families helps you understand where your partner came from. Most likely you have some things in common and some very different traditions too. Although keeping with the old traditions is good, it's also important that you create new traditions with each other. Just like the family traditions in your family creates a sense of belonging and closeness between you and your family, creating new traditions with your partner (and children, if you have any) will create a special bond in this relationship.
5. Let go of the "perfect" holiday
There will be times when you can't afford to buy your partner, children, or family members the special gifts that you would like to. There will be times when there is a tragedy or illness in the family during the holidays and things get shuffled around. There will be those times that challenge what you pictured your holiday "should" be like and you may feel like your holiday has been ruined. This can have a negative impact on your relationship since you're likely to feel depressed/disappointed/agitated and you may even start blaming others. So if it's one of those years, then it just is. Let go of what "should" be and make the most of what is. There is no such thing as a perfect Thanksgiving or Christmas, and years from now you will look back with relief at how you got through such an "imperfect" holiday.