Remember, a light touch on the blade! Some say the weight of the knife is all you need. If you are tense and stressed, you may put too much pressure on the blade. Thin foil will cut easily... go easy, trim one panel at a time!
Want to try something different? For long, thin chrome strips, use "eyeball measuring" to cut the foil to the correct width... right on the sheet. Then peel it up, and apply it like yow were adding pinstriping tape to a car. If it doesn't lay down straight, peel it up and try again.
No matter how you do it, save the final burnishing for last; after all the trimming. I know you will do just fine!