In my experience there are two very good reasons for pressing the pieces of fabric which will become a cloth doll or doll outfit before sewing them together.
First, as I said, these tend to be very small pieces of fabric, once the pattern pieces have been cut out. Ironing these pieces before they are sewn together means you are ironing, or pressing flat pieces of fabric. Once the doll or clothes are sewn together, the pieces are even smaller because the seam allowance is already used; and trying to fit an iron into a doll sleeve is essentially impossible. If you want a nice, crisp finished product, without all the folds and creases in the original fabric, press the fabric before sewing.
Second, Pressing the turned under hem and seam allowances makes the actual sewing go much easier and quicker.
As you can see in the photo at right, in the lower left corner is a dress bodice that has been sewn together at the shoulder seams and the seam has been pressed open. This makes fitting the gathered sleeve much easier and results in a flatter shoulder seam.
In the upper portion of the photo is the skirt with the hem turned under to the wrong side and pressed in place. Actually stitching the hem is a breeze once the fold is pressed in place.
The area pictured in the photo is only about six square inches, so as you can see these dress parts are for a very small dress which will sew up neat and crisp and will not need to be pressed after being sewn.
Index of Doll Costumes
Index of Special Doll Making Techniques
Clothes for American Girl and Similar Dolls
The most popular dress on the Doll Making Site, The Spring Dress for 18 Inch Dolls, is included as well as 5 other outfits, underwear, and accessories such as jewelry, a bag, a knitted hat and scarf, and the new scrub suit. There are also patterns for slender Magic Attic type dolls as well as full-bodied American Girl dolls and an antique Saucy Walker doll from the 1950's.
If you love 18 inch dolls, and want a collection of patterns for a wardrobe, all in one handy Ebook, this is for you! All these patterns are available on the Doll Making site, but I have brought them all together in one book for ease of finding and using them. Make Clothes for 18 Inch Dolls.