When birthdays, Christmas, or other gift giving opportunities come up, don’t be hard to shop for. It often helps to make your spouse a specific list of suggestions of things that you might want.
One thing that I do throughout the year is when I see something I like, I go to Amazon.com and add it to a Wish List. Many similar retail sites have a feature like this where you can save things for later and even share them with another person through email. When I do this when I’m thinking about it, it makes it a little easier to do than to sit down all at once and try to think about what I want.
You might also consider requesting gifts that are experiences rather than just things. For example, getting your spouse a hotel stay paying for a babysitter so that the two of you can go overnight without the kids and a gift card for a nice dinner. You might get tickets to go see something in the theater, or to a sporting event that you want both want to go to. Sometimes memories are the best gifts.