@Ana1234 - It's not rocket science either though. I find it's just a matter of making sure that you've got pretty good odds. Don't just take one cutting of anything, make sure you get several (although be respectful of the plant you are taking it from, of course).
My father used to stop on the road all the time and take cuttings from plants that he liked the look of and they did often grow well. But he was the kind of person who would encourage you to make your own rooting hormone and he didn't like commercial preparations at all. He used the willow water method described in the article.