Once it's on the car or when spraying? When spraying, you just change the amount of air versus paint/clear is being sprayed out. I'd recommend doing at least 4 coats of clear, I did 5 on the Civic.

Thinner coats tack better to the paint and tend to lay more evenly. I usually mix just a tad bit of clear into the paint mixture itself before spraying.

Once on the car, wetsanding is the only way to reduce the clear.