One of the biggest mistakes I see with washes is about 90% of them are dark... when many of them should be lighter. In helping fake a material property or surface type or value (light/dark) it's sometimes more helpful to run a wash of lighter color through an area. These tend to need to be a bit heavier than your normal wash solution (per cent of paint to thinner) but are much more effective. Also, look for opportunites to do some work on the model/panel edges, not just in the recesses... or as you see, they look fake.
Learning to dry brush edges efectively can be as good as running a wash through an area.
For the washes that you do use, never use black. Try to find a good color chart and really study what happens when certain colors (even metals have a color bias) turn dark... seriously, study these. Also, you'll notice that with some metals (well, this is basic color theory, but certain metals really kick this up) ...anyway, some metals will have a warm or cool hue, being bluish or brownish... you want to run the OPPOSITE (complement) color into the panels. This is definitely true for birgher and colored surfaces. Study the color of shadows.
Last, don't be too quick to use washes, let the model sit for a few days. Depending on the scale, you may find that ambient lighting does enough to knock the panels into relief. If so, then maybe run a complementary colory through the lines, but don't try to infulence how much it pops (light or dark)
