I've had little luck trying to...

Try this: Remove the pit from the avocado and wrap it in a moist paper towel. (You may have better luck if you use a pit that has not been refrigerated.) Put the paper towel and pit into a plastic bag and seal it. Keep the bag in a warm place and check it every few days. If the towel dries out, remoisten it. When roots appear, place the pit into a pot with potting soil.