I left every opacity/blending option off and neutral, so you can experiment it yourself and get the best results possible.
In case of the rivets or panel lines, it's pretty simple.
The panel lines and rivets are done in red for visibility. All you have to do is create a new layer, ctrl+click the panel line/rivet layer, and then paint over the new layer with the selection from the PL/Riv layer.
Use a super-size 2500 brush, choose the color most appropriate for your current skin, and stamp it down twice.
