I have been carrying out cosmetic acupuncture treatments for over 5 years now and the results do vary, but are always good. I have recently been experimenting with retaining the needles during treatments for longer than I have done in the past.
The way to do this is to insert the needles in the facial points and then leave the patient to relax, perhaps listen to some music and generally unwind. Obviously patients cannot lie on your couch for hours at a time, but if you can squeeze 20-30 minutes into a treatment you will achieve some fantastic results, also you will find the face starts to eject the needles if left any longer than this.
Try experimenting during treatments to find the optimum time that you leave the needles in to achieve the best results.