So to recap from part 1.
Step 1: Prime the Model
Step 2: Base Coat the Model
Step 3: Paint the detail work.
On to step 4. This one of the easier and quicker steps. Grab a large paint brush and a pot of GW's wash Devil mud. And go to town on the model. don't be shy or timid here, the new GW washes add instant depth and detail to any paint job. It takes a long while for the wash to dry and you need it almost 100% dry to do any more work on it, otherwise you will rub off the wash when you touch the model.
Step 5 is basing the model. If you glued on the sand before priming you can paint it. I start with a dark color, for my Chaos I used Scorched Brown. Once that dries totally I dry brush the flock with Snake-Bite Leather, its gives the sand a dity mudy look. Finally once wash is totally 100% dry I use super glue and add in a few patchs of Grass to the base. It ends up looking pretty good. Here is my Final product terminator
Its a good looking model and it is one of the fastest ways to pump out models. I personally hate painting large numbers of models. I tend to use dark colors becuase they hide mistakes better. And as anyone will tell you painted models look better then gray models every time.