It was an argument that I lost with my husband when the kids were young and money was tight. The kids aren't so young anymore, but money is still tight...and I still think it was a really good idea.
"How about learning to give the boys haircuts?" Their father -- a carpenter by profession and, well, good with his hands (which I am not) wouldn't consider it.
But if he had (or if I could have risked it) here's how I would have proceeded:
First, I'd have taken the boys to their barber, Bill, told him what I was planning, and asked him to show me what he was doing and to recommend the easiest tools for a novice to use. Not all barbers would be receptive. Bill would have been glad to help. Whether or not your hairstylist will advise you, you'd still want to start with a good professional haircut. After that, you follow the cut.
I'd use interlibrary loan and read some books, or even better borrow a DVD, on basic haircutting. These days, there's probably a symposium on the topic on Youtube.
Then I'd start pricing supplies, which might be nothing more than the right pair of scissors (although I suspect I'd need several kinds).
If I still wasn't sure that I could do the job, I'd ask a friend in the business to come over to supervise the first cut. If I didn't have a friend, I'd offer to pay a barber for a one time consultation at home, which, of course, negates the whole exercise in the first place...until you consider the savings over time.
I do have to caution, however, that you risk turning your child into a social pariah if you plan on giving him a bowl cut in the interest of saving money. No bad, amateurish, ill-advised hair cut is worth it. Even a $12 Supercuts hack job is better than letting your child go to school with a mullet. He will pay for that for the rest of his school career. There are lots of affordable hair cutting options out there, especially for younger children.
But my larger point is that if we've learned anything in this time of cost consciousness, it's that we've gotten lazy. It's been a long time habit just to pay for what we need. It's made us afraid to try new things.
As for the kids, I'd have been sure to be competitive with the barber shop -- which at the very least would mean lollipops.
Real frugal: Cut your kids' hair at home