The really tricky part is heads, but there are lots of tutorials out there. One thing in particular that seems to be most important in head modeling is edge loops. This is a bit like putting an elastic band on your head; really it's just an aid to keep the model smooth and also ensure that the detail is spent where needed most.
The main thing with the other areas is to use a guide, either a sketched character concept, photograph, or even an existing 3D model. There's no shame in grabbing MakeHuman, and using it's crazy polygon count models act as a guide. In fact that's just what I would do. For the sake of sanity, make a male and female character, naked of course - and use those as a start point - you might even be able to simply vertex edit legs to give trousers - having a generic shaped and UV mapped template would save you a lot of time. If you use the same mesh pretty much, then you can use the same animation skeleton and basic keyframes. Consider the big picture, because you'll get better and better as you go on, and you don't really want a vast difference in quality. It can take a bit of organizing to preserve continuity.
The model is incredibly low polygon, which is perfect if your making Warcraft3, but in a 3D FPS game for instance, you should really use a minimum of 1000 polygons in a character, 1000-2000 polygon character models are pretty good for FPS games in DBPro. You can only really get away with less if you use normal mapped detail, which can be a right pain to get nice.
He looks cool though, I think you got a lot of character in there, looks like a p'd off machine operator. He looks a lot like a Steve to me
.
