Mix the base coat with a lighter bluish grey. Using that mix, carefully paint all raised detail except that which would not be exposed to light in any way (such as the part of the saddle at right in the shadows). At this stage it is ok to have most of the detail painted in the lighter tone if it is actually exposed to light in any way.
Carefully go over all areas that have more exposure to light with a mixture of the second tone and white. (see sidebar on the best way to tell where to apply the paint). At this stage it's starting to look like something. Be careful however at this stage not to over do it.
Now for the very highest highlights use a very light grey applying it only to areas that would catch the most light. Again, with silver, unlike god, you will have more areas that reflect light. Look at the arrows at right to see.
Viola! You're done. While time consuming, because you are effectively just layering the paint, it is not as overly complicated as you might think. The most important aspect to understand is the effect and position of the lightsource you are trying to replicate. Without an understanding of that, the whole thing will just blend into itself and will end up looking white.
There are actually two ways to practice this technique that might help you learn the effect of light more quickly. One is real easy, simply look at paintings of soldier wearing lace. You'll see that the artist replicates the lace using yellows or whites and grays only yet your eye is fooled into thinking it is actually metallic only because the manipulation of light. The other method is to photograph your figure under a lamp and note carefully where the light hits and where it doesn't. The best thing to do is to prime you figure, place a 100 watt lamp over it (do not use flash) wherever you would like to see the light coming from, and photograph it. You will see EXACTLY where the shadows and highlights are supposed to go.