I have done a little bit so am far from an expert but here is what I did. I firmly taped a paper image of what I wanted to a piece of frisket paper. I then cut both the paper image and frisket paper by folowing the lines on the paper image with my hobby knife.

The marking on my combat models F-16 were done using this method. The kit supplier supplied the paper templates so I did not have to create them myself.