i always start over a black under coat but if starting from white you might want to basecoat the metal parts black.
no matter what type of metal i'm doing i always then do a basecoat of tinbitz. this covers really well and most of the other metallics go over it better than any other basecoat that i've found.
for bright shiny silver i would then go bolt gun metal basecoat then heavy drybrush of silver.
follow this with several very thin washes of black and blue inks. for your models i would use the washes to line the creases then maybe draw out some of the colour with a clean, damp brush - the idea is to drag the ink out, making it thinner the further you get from the crease and thus creating a smooth transition.
i also find that the metalics are great for drybrushing anyway and if the above blending technique described above sounds a bit complex then go back to the washes step and cover the whole area until you get the shaddow colour as you want it before drybrushing the silver highlite.
tip 1.
always shake the bottle hard before using, esp if it has sat on your shelf for a while. if it still hasn't mixed properly (usually the case with the hexagonal bottles with the screw top) hand mix with a bent paper clip.
note - i really don't like those bottles and have thrown away quite a few of my metallics from that period. i still have the original flip top ones anyway (i think coat d'arms are the original paint makers and they may still do their own range with different names - i leave others to add to this point). the new flip top tin bitz, so far, is great, but paints don't always age well (although i'm still using some i bought back in the late 80's!).
i don't like the foundation gunmetal so far - not great coverage & was hoping to leave out the tinbitz stage.
hopefully this will get rid of the lumps.
tip 2.
metallics love ink washes and drybrushes. sometimes i do several rounds until i get the result i want.
tip 3.
don't try
nmm unless you are really good! i've tried it several times and i have had no luck so far.
here's some egs of my work -
http://i301.photobucket.com/albums/nn53/bubber1234/VAMPR.jpg
http://i301.photobucket.com/albums/nn53/bubber1234/VAML.jpg
http://i301.photobucket.com/albums/nn53/bubber1234/MINR.jpg
http://i301.photobucket.com/albums/nn53/bubber1234/bloatfrontright.jpg