Dazman, depends on what you want to do with the tank and what type of tank. I prefer metal tracks for the weight and traction. I clean them well with soap and water, let them dry for two days, then paint them Model Masters Rust. After 24 hours of drying for that, I then just haze on flat black. As you run the metal tracks, the contact areas wear the paint off and become shiney, like the real thing.
Some tanks run well with metal tracks out of the box. Some need small upgrades, some a lot of upgrades. Again, it depends on how you run the tank, are you going to battle with it (lots of extra stress and strain in combat) and the type of material you actuallly run it in, and first and foremost what brand and model tank do you have.
Give us an idea of these specs, and we can help you more.
Sev