If the atomizer is clean (I recommend blowing it out each time you sit down to drip or change flavors), use three drops to start. When it starts to go dry, re-wet it with two more drops. You can start with four drops, but it might be too juicy. You can re-wet with 3 drops, sometimes that is better than two, but if you do that a couple times in a row, it will probably get too juicy and have to be blown out again. After re-wetting with two drops 5-10 times, you might want to blow out the atomizer again and start over with three, for best results.