I just primed my new steam tank. Now I am lost. I don't know how I should paint the tank. I want it to be orginal but also empirish. please help.

I don't know exactly what it looks like, but I'd make it beigish (probably a mix of bleached bone and snakebite leather), making the metal parts chainmail or any other metalic color of your choice.

That sounds like a pretty good color scheme, it just might look a little bit too 40k'ish. If it is one of the first tanks, they might not take camouflage into consideration. I would just picture it mostly all metallic, tin and copper colors mostly and probably some symbols of royalty if you can paint them.

What does the rest of your army look like? What are your army's main colors?

Ditch the steam tank and take something that isn't cheap. :P Seriously though it should fit in with the colour scheme of your army, so where are they coming from?