I have no formal training as a hairdresser but have been cutting, setting and perming the hair of a number of my family members for years. Certainly there are obvious dangers in such a daring pursuit, but my victims aka customers have come away relatively safely over the years.
Nana's single attempt to trim her husband's hair once, long, long ago did not turn out so well, and so she was never asked to repeat her performance. The story of how she neatly shaved off all the hair on the back of his head, with what turned out to be one of those newfangled pet hair trimmers he'd bought at a flea market, remains in the family archives as one of the funniest things she ever did in her life.
Not much more than a year into my marriage to my darling husband, when we were still living with his parents, I walked in on Nana's bi-weekly self-directed wash and set. Aside from the numbness and tingling in her hands from keeping them suspended above her head for about fifty tiny rollers her shoulder was acting up from long term osteoarthritis. Naturally I offered to help and ended up as her regular hairdresser.
I graduated from washing, conditioning and setting her hair, to home-cutting and perming thanks to 'Toni'.
My tried and true method of simply cutting off the same length of hair from each section that had grown out worked to keep her simple halo of curls in check and to keep my husband with the same universal cut he's had since the day I met him. (His numerous bad hair experiences with barbers who wouldn't listen kept him from going to professionals, and yet had him trusting me with his doo, go figure.)
I don't trim Grampa George's hair, but do apply gel and comb it out for him after I've toweled it dry after every shower. And I've trimmed his mustache now and again when it begins to interfere with mealtimes.
My children have long outgrown the haphazard bangs trims and other hair experiments I've doled out over the years, but look back lovingly on family and school photos to remind me of my limited scissors skills. They always look amazing now since they trust the professionals to keep their tresses trimmed.
Nana still gets her three to four perms a year, her hair the same tough dry consistency it's always been. There aren't any bald spots though it tends to flatten at the back since she sits and sleeps a lot. It grows fast enough to force me to do regular spot trims along her collar line, but she's a happy customer who always give me a tip when I'm done: rinse well, dear.