This is a tip that was brought to my attention by John Bessie, a member of our club:
After cutting the section of foil and applying it to the appropriate area on your model, use a soft bristled toothbrush to burnish the foil onto the contours of the underlying detail. As a bonus, if your brush has the rubber gum stimulator on the handle, you can use the tip to make sure that the foil is completely settled on any scripts or emblems.