Choose a plant and stem:
The first step is to choose a strong plant which can repair itself. On this plant go for mature relatively thick stem. It is preferable if you go for a non flowering stem. Get hold of cutting instruments like gardening scissors. However, make sure that it should be sharp so that the cut is neat and clear. Keep high care of hygiene. Your hands and the instrument should be clean because the cut makes the plant vulnerable to disease. Stem cuttings from the upper part of the plant are more successful.
The lower one third should be completely leaf and bud free because it will be put into the ground. So remove all the leaves and buds from this section. You can leave the upper leaves.
Dig a several inches hole in the soil and place the bottom of the stem into it and cover with soil. Don't waste so much time on cutting the stem and planting it, as the chances of success gradually reduces with time. Water and take care of the plant accordingly. You can also put a cloche over your stem to encourage growth.