I carefully remove the flashing and other unwanted metal being sure I don't scratch details on the miniature. Then I stick the crew, using white glue, to pieces of card so I can handle the figures without touching the miniature and rubbing off paint with my fingers.
To get a nice even colour I painted in two light coats. This is better than a single heavy coat as the paint dries evenly and does not get "chunky". As you can see the gun is pretty bland in a single colour. I am going to create the illusion of depth by highlighting raised parts on the gun with a lighter colour. I added some Goblin Green to the mix I had previously and used a technique called dry brushing to get just the raised bits. Here is a comparison: the gun in the foreground has been highlighted, the other one is just flat colour.
There are two tricks to dry brushing. First you need to wipe the brush on a paper towel until the lines of colour are very faint and second, contrary to the name, the brush has to be a little damp to avoid the paint drying out too much and leaving a "dusty" effect all over the miniature. To apply the highlights lightly drag the brush over the miniature. All the raised portions will rub against the brush and the small amount of remaining paint will stick to the miniature. The amount of pressure is directly proprtional to the amount of paint remaining. Don't push to hard though or the lower layers could be scratched off.
I spent the rest of the night just experimenting with colours since I don't have the exact colours that the Flames of War source book calls for. Here are the results of the gun crew's pants.