There are a few different methods you can use to do this. This guide will go over two of them. Method 1 requires a printer and works best for larger dolls, such as SD BJDs. The second method (Method 2) does not require a printer and works better for smaller dolls such as Barbies. Of course, either method can be used for any type of doll.
It should be note that since most dolls' porportions are exagerated, you will need to make a mock up (or a couple) before you cut on your good quality fabric. If this is something you are making on a deadline, please keep in mind that you will need to do this. I have found that if the item has more than one size, its best to cut the sides of the pattern to the smallest size and the tops and bottoms to the largest size.
Method 1
Method 2