I did the base color coats and then hit the whole canopy with a couple clear coats. Then I print a mirror image on the paper with a laser printer and cut it so that there is a good 1cm margin around the image.
If I am working with a flat surface or one with a single curve, such as a cylinder, I simply use masking tape to hold the paper firmly in the correct location. If I am working with a double curve, like a sphere, then I will get the paper slightly wet and then form it to the canopy and work out the wrinkles and then secure into place with masking tape.
I then hit the back of the paper with the tip of a heated iron, working carefully so that I don't press down too hard while moving the iron, thus ripping or moving the paper. Gentle pressure is all that is needed and I usually go over the whole thing a few times, giving each spot about 20-30 seconds of direct heat.
Once this is done, I apply water to my fingers and rub the paper until it disintegrates and leaves only the toner stuck to the paint. I then remove the masking tape and continue to rub the area with a moistened thumb until I get as much of the paper off without going too far and rubbing the toner off. Once the area dries, the paper might be visible, but as long as it is invisible when wet, it should be that way once clear coated. Once I am happy with the area, I hit it with clear coat.