After handing in for 1st Submittal I also did some extra details to the Tank. I was stuck with texturing in Photoshop over a lot of Easter so once we got back to uni I was able to texture in Mudbox which is so much nicer to use while texturing!
I've been dirtying him up the past few days while also finishing off my Business Studies work, so not much has been added, but here's what I've done with the dirt so far. The greener bits around the hard skin is a falloff of subtler hard skin, so that the actual bits of hard skin don't look as if it's just attached to the body, now it looks more like it's growing around it. The dirt on the face is actual dirt, but I've only managed to add it to the head so far: