I was on 16 nic but it was strong and i was coughing from it. So i got 12 nic. I guess everyone is different and i just have to stop the analogs and see what happens after a few days.
Inhaling straight into your lungs can be harsh. If you are doing this try a drag into your mouth first, then inhale. The amount of vapor you inhale makes a difference too, so taking a shorter drag will give you a lighter, more gentle vape experience.
The suggetion to try higher VG content is a good one. I vape mostly 50/50 pg/vg and have had no issues with any clearos I've used. If your juice does get really thick and you have issues, add a drop or two of water to a tank. That will thin it pretty quick. If that works for you, get some distilled water and you're set.
I smoked a pad for 37 years. I started with 18 mg and went down to 12 after a few months. I was noticing headaches when I vaped too much which I did to fight off cravings and was why I first lowered the nic. The cravings definitely get better over time, but we are all different in this regard. Take it easy on yourself. If it takes you a few months or a year to totally loose the smokes, so be it. Every cigarette you don't have is a victory!