Whether you are close to your daughter-in-law or just getting to know her, finding the perfect Christmas gift for her is important. To do this, you have to find a gift that speaks specifically to her. It needs to be something that she really would want to use and appreciate. If it is, it'll say you care enough to listen or to put time and thought into her present. It hopefully says welcome to my family. In fact, it possibly says a lot more than the two of you know how to say to each other, yet.
To say all this, you need to know or find out a little about your daughter-in-law. She very well may be nothing like you or your daughter(s). Her interests may be totally foreign and uninteresting to you, but go with hers. Just try to avoid giving gift cards or money if you can help it. They tend to say that you couldn't be bothered to figure out what she really wanted. The possible exception would be if she's seriously strapped for funds and you get a gift card to her favorite store. But even then, try to dress it up with a thoughtful card at least or possibly a box of her favorite chocolates.
So what is she into? If she's an avid reader find out if there are any new books she's been dying to get her hands on, or find a fancy collector's edition of her favorite novel of all time. If she doesn't already have one, consider buying her a Kindle or something like it.
On the other hand, perhaps she's a music lover. Think concert tickets or her favorite artist's new CD, as long as you've checked that she doesn't already have it. Is she an art lover? Try a museum pass, art supplies, or sign her up for an art class. Would taking it with her be a good way for the two of you to bond?
Maybe she's a foodie trying to turn chef. Think fancy cookbooks possibly pared with unique, hard-to-find ingredients or spices. However, kitchen-related gifts are a bad idea if she's insecure about her cooking abilities, no matter how much you want to help. Try to turn her hobby into the perfect gift because you want her to love it, not because you want to help her or change her in any way.
If her hobby is an unfamiliar and intimidating road to take, consider a gift that pampers her. Possibly a gift certificate for a massage or a manicure. Maybe buy her a personal piece of jewelry or something that she'd like, but might not spend the money on for herself.
Are she and your son just starting out? Then they probably don't have many holiday decorations, as those usually take years to gather. Consider starting them out with handmade stockings just for them, keeping in mind her style.
Do you have daughters of your own? Give her the same thing to let her know she belongs in the gang. Enlist your son's opinion. He should be able to help, as he knows her best. Take advantage of this chance to get to know her better while showing you care!