The simple, no sew solution, to dressing a tiny sock doll, is to use the cuff left over from making the doll. This works especially well if the cuff is frilly, or decorative. Turn the cuff, so the frilly part is down, and cut a couple of slits for the dolls arms to fit through. Slip the cuff onto the doll, and turn down the top part, to make a collar. You might want to add a few quick stitches, to hold the collar in place, but this is not absolutely necessary.
If you do not have a pretty cuff to make a dress out of, or if you prefer a dress with sleeves to cover the arm seams of the doll, then the process is a little more complicated - but only a little.
Start with a scrap of fabric as wide as the doll's outstretched arms, and slightly more than twice the length you want for the dress. If you don't want to sew a hem, then trim around the fabric with pinking shears.
Fold the fabric in half. Cut a half circle in the middle of the fold, and slip it over the head of the doll, with the right sides in.
Hand stitch around the doll, from the bottom edge of the dress, up to, and around, the bottom of the arm, on both sides of the doll.
Slip the dress off of the doll, and turn it right side out. Then, place it back on the doll, and run a gathering stitch around the collar (just a real loose in and out stitch, all the way around, that you pull tight, and tie off at the end). Trim the sleeves with pinking shears, or hem to the desired length, and you are done.
If the dress looks too plain to you, you can always fancy it up, with a bit of lace or ribbon.
For a boy doll, or alien, follow the same instructions above, but stitch an upside down "v", up from the bottom edge, between the legs, to make pants. And, run a quick stitch, back and forth, through the middle of doll, once you have the outfit the right way out, to create a waistline.
And, just in case you are making an alien, or an astronaut, the bottom half, of the plastic bubble, that toys come in from grocery store vending machines - works pretty well, for a tiny space helmet.
It's great to be a homeschooler.