Hello friends, this is my first try using NMM, but i realize that something is missing, the effect is not so well, could please some one help me?

I think you should choosen here for real metallics.
The NMM technique is in my opinion for golden and silver lace, what in reality is not metallic.

Marc

since you are trying NMM's you probably already know they can be used to create any color of metal, red, green, blue, silver, gold etc.. If you are trying only to create a realistic silver you can just use very thin (well placed) coates of black over a white base coat. the first pass with the thin black will actually appear gray because of the white under layer. Each new pass of black makes the grey darker and darker. Make sure your highest high lite is about pure white and it should be a sharp edge highlite to create the shine. If you want more fantasy looking metal add some purples and blues in there. You'll also want to have some shine lines (I don't know the technical term) a good reference for this would be some paintings that depict shiny objects such as christmas ornament bulbs or even of chrome things like bumpers on cars. It is a very hard thing to pull off but when it is done properly it looks 10x better than metallic paint (In my opinion). Don't give up and keep us posted on your progress.

Hola Carlos!

There was a recent discussion on NMM here:
http://www.planetfigure.com/forums/showthread.php?t=42034&highlight=nmm

All the best!

Thank you friends for all the help and kindly answers. I have done a little more:

Bonjour
Si tu permets je vais te répondre en français...j'espère que tu le comprend
Alors le principal problème est que ton NMM manque de contraste et de richesse dans les teintes
Une surface métallique qui reçoit de la lumière est fortement contrastée, ça part du presque noir au blanc pur pour les reflets
Tu dois reprendres ces surfaces en ajoutant d'autres teintes aussi, peut être du vert, du bleu, du marron dans certaines ombres
Penses quand tu feras les ultimes lumièresn qu'elles se font sur des zones trés étroites, plus le métal est poli, plus ces lumières sont intenses et localisées
Ce n'est pas pour te décourager, mais le NMM est une technique assez difficile à maitriser, mais avec du travail on y arrive

Exactly, very well said. Bring that highest highlite to pure white with a razor sharp line, this will give the appearance of shine. and blend into the darkest areas with some purples and blues. You are getting there but it will be frustrating especially on your first try. Actually I've tried it about eight times now and it is still frustrating.