Vaping does take a bit of getting used to. It's different than smoking. I coughed quite a bit when I first started vaping.
When you say "lung hits" are you trying to draw directly into your lungs, or are you drawing the vape into your mouth first? For most people the second is better (although there are some who like to go straight to the lungs).
PG and nicotine both contribute to the harshness. You could try adding a little VG (which you can get at most drug stores, wal-mart, etc) to try to tone down the harshness. You can also try a lower power/voltage level.
Good luck, and welcome to ECF!