Also:
If members of your family are not able or willing to follow your traditions and/or come to your celebration one year, do not assume it is a personal rejection of you, your family, your religion, or your tradition-it may just be the desire for a change, due to work requirements, or due to a change in the family structure, like a marriage, divorce, or new baby, that requires some degree of compromise. Respect it without guilt-tripping-even if it is likely to be your last celebration of the holiday in your lifetime.
If you are going to be with persons of other religious or cultural backgrounds or traditions, respect their beliefs and traditions, don't patronize them, and don't use the occasion to proselytize or condemn them for their beliefs.
Don't make unilateral non-family plans for the holidays themselves that don't take into account the probable non-availability of others and hold them accountable for not participating.
Respect the possibility that people you expect to exchange gifts with might not be able to give gifts of the same financial value during bad economic times as in the past-including none at all. Be prepared to graciously accept token gifts, like cards, if that's all they can afford to give and don't try to estimate their budgets or financial resources.