I first cut off the doors of the hull. If you do this, I recommend you to glue the doors before you paint base color.
And then I sprayed car primer with an airbrush from 30cm away several times. I think it gave a nice rough texture like studio model AT-ATs. The doors should not be glued at this point because if you do that, the doors would be placed in deep places because of the primer.
After the base color I added dirt streaking and blast marks. I used a pencil to draw them and extended with a finger. Stencil didn't work on them for me. As for the snow effect, I used marble powder. I hope it helps!