Any Primer works (Krylon Spray Primer, such as you get from Wal Mart, I find works the best). Under coat with any black. To do your basic color, a dry brush of 50%/%50 Flat Medium Green/Flat Dark Green from Testors (the acrylics are quite good), OR Use Valejo's Russian Armor, OR Use 75%/25% of Flat Russian Armor Green/Flat Black from Testors (still good paints, but the Russian Armor Green from Testors is a little bit too bright without being darkened).
Once you have your base coat, you can paint details, top-coat and go straight to "table ready", OR depending how detailed you want to get, you can highlight and/or weather.
*If you want to weather your vehicles, Soviet Tanks were primed with a red-oxide colored primer paint, so do a transition of reddish-brown to steel in any area you want to simulate paint wear.