I may get flamed for this, and it will tell you that I am no body man, but I once repaired a panel with just spray cans it was nearly unnoticeable.
I started with by getting to clean metal(and I welded/ground a patch), then wax and grease remover. in your case, if you don't have rust, you just need a rough surface to get the paint to stick. Any deep gouges may need filler to level the surface. Still prep with wax and grease remover either way.
I used all compatible duplicolor products. Roughed up with 400 grit, self etch, primer sealer. I masked the area larger than necessary, and after the final prime I pulled the tape and knocked down the edge with 600 wet sand paper.
Then I did color, and clear without masking. This allowed me to buff and blend the clear almost seamlessly.
As stated, I used all duplicolor, but whatever you use, get color and clear together. Non compatible products will ruin your results.