We've used this tried and true method for years... it comes from Sunset Gardening which I found several years ago...
Start in the morning, when growth is freshest. You need sharp clippers and a plastic bag. Look for nonflowering shoots that are mature enough to snap when bent. Make a clean diagonal cut 2 to 4 inches from the tip of the shoot, just below a leaf. Put the cuttings in the plastic bag to keep them from wilting.
Next you need a coarse, sterile, moistureholding soil medium such as perlite, vermiculite, or sand. We used equal parts vermiculite (to hold moisture) and perlite (to keep soil from getting soggy).
To prepare a cutting, pinch off lower leaves. Dip the leafless end in rooting hormone if you like. Poke a 1 1/2- to 2-inchdeep hole in the rooting soil, insert the cutting, and push soil around it. Plant three cuttings to a 4-inch pot; water, and put pots in a humidity chamber. To prevent it from drying out, put the chamber in shade, and mist plants frequently.
In about a month, roots should be at least 1/2 inch long. To test, tug cutting gently; if it resists, it's ready to transplant into a small container of potting soil.
Water and fertilize regularly. When plants are well rooted and of good size, transplant them into the garden or share them with friends.