Decide which holiday traditions you want to keep and then be sure to start one of your own. Maybe you don't like having the tree up at right after Thanksgiving, even if that is the way it was always done in your parents' home. You would like to pop some popcorn and everyone in the family decorates the beginning of December. It doesn't matter what you do, it should be a memory you want your own children to cherish.
Set a budget and stick with it. Use lay away where possible and avoid maxing out your credit cards. There is nothing more depressing then trying to pay off credit cards bills. Your children will not be able to have everything on their list so help them prioritize what they want the most.
Carry your list with you. When you find something that is just perfect for your Auntie buy it and cross her name off. Keep track of how much you have spent for each child and when you have reached your limit stop buying for them. Shop craft fairs, second hand stores and sales. Try to avoid the week before Christmas rush.
Eat healthy and don't over eat. When we get busy we often tend to eat on the run or grab fast food. Starting with Halloween candy we all tend to nibble and there tends to be more food around, especially rich snacks which we may not eat the rest of the year. Children can develop upset stomachs and otherwise feel badly when they eat too many sweets or high fat foods.
Delegate. If you are having big family meal, decide ahead of time who is bringing what. The children can help with setting the table and cleaning up after.
But most of all, remember that this is a time to spend with family and loved ones, regardless of whether you celebrate Christmas, Hanukah or Kwanzaa. So enjoy.