I think the key is once you get a haircut, or before it gets too out of control, is to “give it a go” in small steps. I think at our age
(grans) we’ve watched our hairdressers give us enough haircuts over the years to give it a try, especially if your one of those ones like me who keeps getting the same cut, or goes back to the same cut time and again. I use a full length mirror, as I think it’s best to do it standing, and try and follow the “hold up sections of hair and snip across taking small cuts off at a time all over. I then do it again and snip into it downwards like you see them do, pretending I’m a professional. I give it a quick brush and if I feel I need a bit more if I repeat the process. I think it’s best to just dampen hair ever so slightly, hardly at all before cutting and then wash your hair . I’ve been amazed by how well it’s turned out.... in fact on some occasions I’ve preferred it to the salon... would you believe!! as for the back.... I just hold the scissors against the back of my neck ( for short hair) and just cut across, and maybe snip from the side view for the back...ALWAYS looks better than before I started. I think I’ve reached that age of “try it” surely no once would cut till they were bald... lovely trim and tidy.