I made pretty good air popped kettle corn like this:

Air pop amount of popcorn desired.

As it comes down from popper spray liberally with Pam cooking spray and alternately sprinkle a mixture of:
1/8 white sugar
1/8 brown sugar
1/2 tsp salt

Spray and sprinkle until desired coating is achieved.

You will have to experiment with how much of this mixture you need for the amount of popcorn you pop, but the proportions are a good salt to sugar ratio for my taste.

There will be a bunch of sugar on the bottom, but to get enough to stick for flavor this seems necessary.

Hope you like it I thought it worked.