...use the shortest guard you have while cutting it with electric clippers.

I have cut my own hair plenty of times, and it usually presents no problems because I know which guards to use on my clippers. I don't use scissors, as that would require skill and I have none.

For some reason, I chose to use the shortest guard I have, 1/8", and run it across the top of my head. Since my hair is light colored, and a tiny bit thinner on top than I'd like, it almost looks as if I'm bald now. Ugh.