I apologize in advance for my pics, they're not very good (and apologies for the mess you can see in my working space too)
STEP 1- Making hair tresses
First we need to measure how long we want our doll's hair to be. It does not need to be exact, just an approximation. Then, pick something rectangular as a book cover, a notebook, a box, CD case... whatever you have at hand that may help us getting this hair length. It must be something wide enough for the hair to be long. It's better if you get a long hair at first since you always can trim it out later, but you cannot grow it up if you start with a short hair.
Start winding your yarn loosely and evenly around the object you are using (in mi case, I used this notebook which is twice the length of hair I want my doll to have from top of the head to shoulders.)
You'll get something like this:
When we have enough yarn, we cut both sides (or just one side if you want super long hair locks)
Divide the yarn in groups. It doesn't matter that the groups of strands are uneven. In fact, I prefer the results in the doll if we use the thicker ones in the front and the thiner ones in the back.
With one of the strands we tie the cut yarn up in half, like this:
This would be the hair line in the top of the hair. I tied them in the middle because I wanted a hair with a part in the middle, but if you want your doll's hair part to the left or the right, tie the yarn accordingly.
STEP 2- Sewing
I like to pin the hair before sewing to see how it looks.
When we are ready, we start sewing in the part of the hair. Try to use a thread similar to the hair color so it doesn't show. (You may use a contrast color if that's the desired effect. For example, using black thread in a blond doll to simulate the hair roots starting to show over the dye)
Once sewn, you should get something like this:
Now, here's a trick I learned from Silvia. You can sew some of the strands of the under layers to the head so the head color doesn't show under the hair, covering bald spots. Another trick: crochet your doll head rounds in half hair color half skin color so it is easier to cover those bald spots.
Sew in between the strands and the head alternatively so the hair stays in place.
Now it is completely sewn, time to trim the hair tips evenly...
.... and style her hair just as you wanted.
And she's done! In this case, since my doll was a bride, I added a pearl crown to add glamour to her hair style.
I hope this tutorial is clear enough and easy to follow. Please if you have any questions, just let me know.
And of course, if you use this trick to make and attach hair to you amigurumi doll, I'd love to see pics of the results!
Happy crocheting and hair styling!