I had a friend shave my head for me last time it got too long, but I believe in self reliance and I decided that if I couldn't maintain it myself then I didn't deserve this awesome haircut. Also, that friend is in Canada and I'm in California, so I was on my own as far as hair cutting was concerned.
Step 1: Materials
-big garbage bag (to wear as a smock)
-clippers (I ended up using two different models, but more on that later.)
-scissors (to cut arm and neck holes in the garbage bag)
Last time I got my hair cut I wore an old t-shirt that I didn't care about, figuring I could wash it afterwards. It got so many little hairs stuck in the fabric and no amount of washing would get them out. This time, I found a box of huge garbage bags in my garage so I decided to just wear one of those to protect my clothes and minimize clean up. It worked great and I would highly recommend it to everyone.
I didn't have any clippers so I bought these on Amazon and I think they were less than $30. I don't know much about clippers but Wahl is a reputable brand and the clippers that I have for my horse are that brand, so I figured they were good enough for me.