I could have written this post....as a matter of fact, I did write one just like it!!

I was in the same boat, coughing with each draw on the e-cig. It got so bad that I walked away from the whole idea of it for a while. Then I wrote a post like yours, got tons of great advice and finally figured things out. What worked for me:
1) I buy my e-juice at 50 pg/ 50 vg. I tried 70pg/30vg, 60pg/40pg but the 50/50 was the sweet spot for me.
2) As much as I wanted to try all the sweet juices, I realized they made it worse - maybe at some point I'll try again, but for me in the beginning, they were too, too sweet and irritated my throat - hence, more coughing.
3) Using 50 pg has a little less TH but I realized I love peppermint flavored juices (Peppermint Twist from HHV's being my favorite) - the peppermint helps with the throat hit - it's just perfect for me.
4) I read all the great advice I got, and even watched some video's on You tube and now I take a few small draw's into my mouth, then inhale.
5) Drink lots of water - I am not a water drinker but vaping is dehydrating and the more dehydrated I'd get, the worse the cough would get. So, an added health bonus - I am now a water drinker and it's helped!
After getting all of this down, figuring out the juice and levels that work best for me, I decided on Sunday morning to give the e-cig another serious go - and have not smoked a cig since Sunday morning at 11!!

Love vaping, do not miss smoking one bit.
Just don't give up - it takes some experimenting and trial and error but it will work and you will stop coughing!