At long last we have heard from you, we were getting worried about you being so quiet!!!!!!
There are not many secrets to hand painting, but like any job common sense, quality tools, time and patience.
First use a good quality what we call coach enamel paint, (none of these modern two packs, with hardners, reducer's and god knows what else)
Second is your brush, here in UK one of the oldest and most famous manufacturers for top quality is the "Harrison" brush, very fine and soft bristles which DO NOT drop out the first time you start to use it as with many cheap ones.
Third all you need is an old camp stove and pan with boiling water, place your paint tin in the boling water and stir well, you will see the paint thin as you stir, remove the tin after approx 15 to 20 minutes and you are ready to go.
Always apply in thin coats as the warm paint hits the colder metal just brush out and cross the pattern, but don't overbrush as the paint quickly drys, as you move across the piece of metal always use the same pattern and you will see the fine brush marks disperse as the paint flows together and drys. These fine brush marks come from the quality of your brush.
Hope this is of some help to you and your experiments, I look forward to hearing how you get on with it and post us the photo's.