You don’t need a whole selection of sewing machine feet for sewing doll clothes, although you can, of course, collect as many as you want. The main feet you will need are the quilting foot, the general purpose foot, and the edging foot.
Among the sewing machine feet you will use most often is the quilting foot. It is constructed with one side measuring one quarter inch on the right side of the presser foot. Quilters usually use a seam allowance of one quarter inch, and this foot allows them to simply use their presser feet to sew quarter inch seams. Doll clothes also usually have quarter inch seams, so a quilting foot is just as handy for you in sewing doll clothes. The right-hand edge of the foot measures exactly one quarter inch, so you can use it as a guide for your seams. This is the foot I use most often.
It is handy to pair a quilting foot with a straight stitch presser plate, sometimes called a throat plate. This is a presser plate with only a small, round hole. You can only do straight stitch with it. It is useful for fine or thin fabrics, to keep them from being “sucked” down the presser plate hole, as often happens with your general purpose plate. Warning: just be sure you change the presser plate before you do zig-zag or fancy stitches, or you will break your needle!
On some modern computerized sewing machines, you can activate a setting that keeps you from sewing anything but straight stitch until you change that setting again - very handy to avoid breaking your needle! My fairly new Pfaff Quilt Expression 720 will even automatically activate the straight stitch only setting when I put on the straight stitch plate. I have to manually deactivate the setting when I remove the plate and presser foot. It's saved me a lot of broken needles, since you're bound to forget when you get busy sewing...
The general purpose foot is the foot you usually use most for sewing. However, it may or may not be so useful for doll sewing, particularly if you are sewing on very fine fabrics. I find I get much better results with the quilting foot (straight stitch foot). However, it you want to sew zigzag, say for overcasting seams, you can't use the quilting foot. You can overcast seams to stop ravelling with this foot if you don't have the edging foot (below). It is also good for other decorative stitches.
Often, modern machines may also have another version of this foot with an indentation under the foot, which allows it to ride over fancy stitches without catching. That would be the foot you would use for the fancier stitches, if your machine produces them.
The edging foot is good for several things. For one thing, you can use it to zig-zag over the raw edges of seams to keep them from raveling. The edging foot has a little wire or piece of metal that holds the edge of the material steady while you zig-zag over the edge. Without it, you just don’t get as neat an edge. I use it for finishing seam edges frequently, since it doesn’t take a lot of thread and produces a thinner finish. I find using a serger or overlocker uses just too much thread and make a very fat seam finish. You want to use a seam finish that produces the least bulk, since doll clothes are small and any bulk will make the seams look way to fat.
Of course, you could finish the seams by hand. This produces even less bulk, but does take more time and patience!
These three feet may be all you need for doll clothes sewing. But, of course, you can add as many sewing machine feet as you want!
You may want to add an embroidery foot, a zipper foot, or a ruffler. A walking foot will help you keep your seams straight and will help you feed tricky fabric. There are an endless number of accessories available for sewing machines. Check with your sewing machine dealer or look in the manual that came with your machine.
An embroidery foot can also be helpful for fancy work. It has an extremely open toe so you can see what you are doing. You can use this foot for fancy stitches built-in or programmed into your machine. Plus it's handy for applying applique--all techniques you can use to make your doll clothes stand out from the generic crowd!