I agree, nmm silver is very hard, especially for beginners, like myself. But I wouldn't give up just yet, there are still a few things you can try.
One is you can search on youtube for "how to paint nmm gold" or at least I think that was it, and there should be a video on how to do nmm, both gold and silver, and even senmm.
Another thing that you can try is what this guy did.
http://www.coolminiornot.com/269470The swords on the tyranids are done in nmm, and if you scroll down, he gives you a link to his website that shows you how to do it. The only problem is that it's in French, so if you can't read French, or have a translator on your computer, then I can tell you the steps if you want(no, I can't read French, but google chrome translates it).
Both of those options require non-GW paints, but work well. I think it would be a good idea to give gold a try though, as it is easier, imo. Also, nmm isn't something you learn overnight, it takes a ton of practice, and lots of experimenting. If you stick with it, I'm sure it'll get easier over time.
Hope this helps!
-Pow