I’d guess if it’s a nightmare then your child probably isn’t ready yet. There’s a huge difference in when children are ready. My children were on the early side, but I know of many people whose children were around 3, and boys generally take longer than girls. I’ve heard that babies in disposables take longer than in cloth nappies, but I don’t know if that’s true.
If you wait till your child is ready it will be easy - or at least easier. My kids never even used a potty - they went straight to the toilet. They probably felt more grown up that way, or perhaps they just didn’t associate the potty with its purpose. We read that you should get a child used to the potty, putting them on before they were ready, still fully clothed, so my husband tried it with our eldest and gave her a magazine to look at. A few days later she asked for her potty, sat down and squealed, “Zine, zine!” (So I wouldn’t recommend that method!)
So my suggestion is a little different to the others: give it a break for a few weeks, let your child see others use the toilet, and then let her or him decide s/he wants to do the same. S/he will.