First, make sure you have covered the repaired area thoroughly. Make sure you have scuffed the paint up to two feet around the repaired area. Now, starting from the edge of the repaired area, gradually spray less and less paint until you are just applying a mist coat approximately one foot all around the repaired area. The idea here is to gradually apply less and less paint so as your eye moves from the original paint to the repaired area you can't really tell where the original paint stops and the repaired area begins. This will take some practice, but when done properly, you will have an excellent repair.

Let the paint dry at least one hour but not more than 24 hours before applying lacquer. Apply the lacquer over the entire area going out about a foot past the edge of the mist coat. Apply full coats of the lacquer (don't mist it at the edges). For best results, take the lacquer right to the edge of the panel you are repairing.

Some metallic colours, such as gold, can be quite frustrating and in my experience I often ended up painting the entire panel, tank etc. Gold fades rapidly and is a very difficult colour to match even by trained professionals.