Bob C.
No magic involved. I'm just lucky, I guess.
I just select a 8" long, pencil diameter, semi-lignified, (never a succulent, juicy, green), terminal branch, with an almost hardened heel. In NYC, the new growth usually is ready for propagation in June-July. I fill a large, green-plastic, soda bottle -(cut the screw top off, evenly, right above the label)- with a quick-draining mix, and plug in the semi-green cutting. I also remove most of the lower leaves and retain a few of the terminal leaves and bud. The cutting should have at least 5 inches buried into the growing medium and a few more inches above the growing medium. I cut another clear soda bottle, at the cap end and just above the label, but this time, I include some of the larger tapered diameter above the label. I cut where the straight sides just begin to curve into the neck of the bottle. When the clear bottle is inverted, the curved tapered section will lock into the lower soda bottle. This creates a little individual "greenhouse" for each cutting, and retains heat and humidity. I should mention that I melt some drainage holes into the bottom bottle, and some air holes into the top bottle for ventilation. I place the bottles holding the cuttings in a sunny window, and keep them warm. The medium is damp, but NOT wet.
I usually see roots after a month, and I wait for the bottle to fill with a good amount of roots. When ready, I just take a sharp scissor and cut through the bottle (at/around the bottom? and cut off the whole bottom of the bottle. Now you are left with a root ball inside a plastic "sleeve". I just push the rooted cutting down and out of the bottle and plant the little fig tree into a waiting, larger container for further training.
Hope this method brings success to those who may try it. I like it because you can keep the individual, newly rooted cuttings growing through the winter if those cuttings are taken late in the season. When spring and warmer weather arrives, you just slip the new trees into a waiting hole in the ground, or into a larger container, with very little root disturbance.
Good luck.
Frank
EDIT: I think I am successful because I am careful about selecting the cuttings at the right stage of development. Again, I never select a soft, juicy, succulent, green twig, but I select only semi-lignified wood, and always include a small section of semi-hard heel.