Cloning is just one of those things that takes practice. You can read everything on the internet and get all the facts and set it all up etc.
But only practice makes perfect.... Sorry, there is nothing I know of to tell you how to get 100% other than what you have already read, but anyone with any method can get 100% given practice and learning what ends up being second nature. Cloning is very very easy, once you get the hang of it.
There are some strains that are very difficult though... I'll grant you that. If by some chance you have one of those, an aerocloner should take care of it.
The only reason I don't always get 100% sucess is due to my own laziness and ignoring them or something, like letting the spider mites takes over and ruin everything I had a month or so back.
I clone in either rockwool or peat pellets. Pellets by far my favorite and fastest to work. Humidity dome for 5 days with 3x a day or so spraying water, then no humidity dome. Light very mimimal the first 5 days, then working up to more.
Aerocloners are even easier.
Those that can't clone to save their lives should buy a bottle of wilt spray and some peat pellets and skip all the other steps and not use a humidity dome and just use one tube flouro.