Whats the best way to colour?

I am creating race track for a futuristic racing game and I am just wanting to know what is the best way to colour in Maya for Unity, im farely new to both programes, should I just do a gravel effect bump mapping, whats the best way to bump map and can you update it later?

your best bet is to texture it in unity. then when you change your textures and resave it Unity will update the textures and the materials its applied to automatically.