Probably the best thing I do for myself over the holidays is to keep my expectations low. Know that a certain amount of shopping is necessary, but keep it to a minimum. Be careful of busy parking lots and crowded stores. They can really set off your anxiety. Try purchasing gift certificates or buying on-line. Avoid drinking alcohol and stay away from holiday parties where drinking and crowds may be an issue. Over-stimulation is something you need to be aware of in order to reduce anxiety and exhaustion. If you're travelling over the holidays take extra care (read my blog post called “travel”).
Be kind to yourself and know your own limits. It's okay to say no. You don't have to attend every event you're invited to. Reduce your obligations. And if you must be somewhere, reduce the amount of time you spend there. Always have a safe person you can go to if you're feeling over-whelmed, and have a place you can go to get away from it all and take a break if need be. Maintain your personal schedule as much as possible – especially eating, sleeping and taking your medication. Exercise, such as yoga, can help too.
Mostly, spend time with those who make you feel comfortable. Rely on your support system and avoid pressure to do the things you really don't want to do. Know that everything will likely not go off without a hitch, but try to go with the flow and just let things be. That will help to control your anxiety and hopefully reduce your risk of bipolar triggers.