1. Make sure you have a really good pair of electric clippers WITH guards. These guards are your ticket to TWA triumph. Do not, I repeat, do not even attempt to cut your own hair without a guard on your clippers. You'll be sorry (ask me how I know). *The guard: That little plastic thing that looks like a wacky comb and clips to the end of your clippers is called the guard. It's also your key to having a wonderful twa. They come in different lengths (I use the 7mm size). The length corresponds to the length you desire your twa to be.
2. Either spritz or wash your hair. I usually spritz because I wash my hair after cutting. Comb through your hair and let it dry just a tad. I say "just a tad" because if you let it dry all the way the shrinking will throw you off when you cut.
3.***Make sure the guard is on your clippers securely.*** Turn the clippers on and start. I usually begin with the front right side of my head, probably because I'm right handed. Push the clippers through your hair all the way to the nape of your neck. Keep going in this fashion, keeping an even rhythm until you make it over to the opposite side. For my left hand side I use my left hand. I'm not ambidextrous, the key is in the guard. While clipping, trust the guard. I press it to my scalp, not hard, but enough to cut through my hair.
When you're done, check to make sure everything is even. I line the back of my twa just a tad but not the front. I have a "W" in the back so I just get rid of the wild hairs outside of the "W". I don't do a hard line. Honestly, this just takes practice. I hold a handheld mirror up with my back facing the medicine cabinet mirror. I've learned how to angle the clippers for an even line.
I use the clippers without the guard. After lining, check to see if you have any hairs sticking up from your twa. If so, take a good pair of hair shears and lightly clip them away in a light skimming fashion around your fro.
For the "clumpy" look, I wet my hair down in the shower after clipping. While my hair is wet I apply about half a palmful of sweet almond oil with an essential oil mixed in (I used sandalwood and cedarwood). I massage the oil in and then rinse as much out as possible with warm water. You may want to have a friend with you the first time.
This will take some practice but you can do it! Good luck!