When children came into the picture, my husband started cutting the boys hair and I would trim the girls. Our oldest is 9 now and he is the only one who has ever had his hair cut by someone other than us and that was only because his aunt is a beautician and wanted to give him is first haircut.
The girls hair wasn't the easiest at first. They both have ended up with chin length hair because they wouldn't stay still. It still turned out cute, but not as long as I wanted. The boys hair was a bit easier, although our youngest son up until about 5 years of age would just cry and cry through the whole process. He does much better now.
We use a Wahl haircutting kit.