On the back of the doll's head, pin every centimeter or so of the section of hair you want to put in, so you're drawing the hairline with pins. I wanted my doll to have hair parted in the middle, so I only did half of the head to start with.
Run the yarn along the side of the part, from the base of the head to the top, then wrap yarn back and forth around the pins. I like to do about four pins' worth on each side before securing. You will have to move some of your pins to accommodate the width of the yarn. I did mine with all three yarns at once, it works well, best even, to work in one color, single thickness. However, three strands goes together faster.
Stitch each section of hair down at every loop. I generally make sure I've stitched them in place two or three times before moving on to the next pin.
When you get to the bottom, work your way back up the other side, the same way.
When you get to the top and have stitched all the loops down, you should have your yarn dangling at the middle top. If it is dangling at the side where the ear should be, that works too, so don't panic.
Put a few pins in the middle of the head, and then some on either side near the ears. Loop it on one side first, stitch in place, then cross over to start the other side. Loop and stitch.
The remaining strands will probably be dangling on the side. If they're at the top, that's okay too. It doesn't matter. Cut the yarn about six inches from where you last anchored it so you have loose ends to work with.Now, just take your crochet hook and run from the nape of the neck up through the hair and out where the loose parts are. Pull through to the bottom by where the loose ends from where you started are.
Cut all the dangling loose strands short.
Make two small yarn balls of appropriately the same size. Sew through them at random angles until you feel secure that they won't come apart.
Pin them just above the ears on either side of the doll's head.
Stitch into place, a lot. A lot a lot.
This is a perfect place to stop if you were after that whole "Princess Leia Rag Doll" look. Of course, I'm never content to stop at just cute, so I threaded my BIG needle with yarn and sewed the yarn through where the balls attacth to the doll, wrapped under the arm and back up to do it a few times in each color, then wrapped around the doll's body, under the arm, and repeated on the other side, in all three colors.
After that's all wrapped and stitched, cut the yarn across the back, slip the yarn loops off the arms, and cut them at the bottom. Tie each pair of strands in a square knot (or a granny knot, it's not that big a deal) just under the little buns.
Admire your cute work.
Of course, you'll want to add a face. I decided she needed some bows, so I tied off two lengths of black yarn around the buns to finish off the look.
If you want to check out more of my Raggedy Rebelz, with their quirky smiles and funky hair, they're hangin' in my Etsy shop: Sock Punky .