Not sure if it's already been mentioned, but I would be cautious about adding bits of metal to your paint as it can actually rust and cause lots of nasty stuff. (That is from experience unfortunately)
As Enion mentioned, it was a very expensive experiment but you have the paints now so it will be good to learn to use them. Personally I find the Vallejo Game colour paints too watery for my tastes and tend to use the Model colour range. These are much better IMO. You can pick these (and the Game colours too btw) in 'themed' packs i.e. fantasy, sci-fi, WW2 and so on. You can obviously also buy them individually, so you might be able to swap the particularly weak colours - orange & red seems to some to mind - and replace them with the lovely carmine red and hot orange
Do keep trying with them though; acrylics might seem a bit alien, but you will be able to do a lot with them once you have some experience under your belt.
Good luck!