To clone rosemary you NEED to scrape off the woody bits that make contact with the soil. (edit: thats where new roots will come from ) About 1 inch is all. I just scrape the woody bits off with a scissor blade. Just like de-barking I guess, dip in root hormone and bung it in a pot. Since I started doing that, 100% cutting success. before that......0% lol.
As for cloning thyme, try burying a length of it sideways just under the soil and popping the end up out of the soil. It will root and send up new shoots from nodes under the soil. When it looks big enough to stand alone, chop it away from the mother plant and pot it up
kiddc: make sure you plant mint in a pot mate. It will take over the whole garden otherwise. It's very invasive and hard to control.