Tracks in mud

I did a tank dio years ago and used Celluclay as the base. I Constructed the base and groung work before the tank was ever thought about. Get the idea of what you want in your head, build the base ( unpainted ) and as the other guys said, imprint the tracks in the "MOIST " ground, to a depth that would be practical for the vehicle and type of ground you want it to represent. Use unpainted tank tracks, tires ect to make the impressions. Aftrer all is done, wash them off, start construction of the model itself. This works really well for me. Just remember to make the WIDTH of the tracks to fit the width of the model.

like sherman said, make the trackmarks before the ground work dries and then, when it dries, you can attach the model to the base. if it is going to be mud, kinda press down firm do get a more of a sinking track mark.

When you make your groundwork, before it dries you can press the model or just the tracks into it to create the track marks.