+1 on the recommendation for Calvin Tan's Osprey book on Painting SS troops.
In so far as the actual painting techniques for camouflage using acrylics, Andy Evans' SBS on LW Splinter cammo on Historicus Forma is an excellent explanation:
Historicus Forma::Painting Splinter Pattern Although the colors and patterns might be different, Andy's example on proper paint thining, laying out the pattern, and shading is useful.
One thing that is most difficult to do when painting cammo patterns is keeping the ratios of colors and shapes correct along with keeping the scale (size) of the pattern elements the same as the figure. A tendency is to start making the pattern elements larger as you get tired of painting - taking short cuts to speed up the process.
Another thing with using acrylics is to keep then very thin and use multiple layers to cover instead of trying to get coverage in only one pass. This will help keep the brush strokes from showing and the paint from getting too thick and "blobby" in spots ruining the smooth finish.
Here's a Hornet figure that I painted using Calvin Tan's pattern sequencing and Evans' advice on "paint management." The camouflage was painted with Vallejo acrylics and shaded using oils (and the rest of the details and flesh areas were also painted in oils). This guy was a practice piece I painted to get some mojo for a series of figures in WH Splinter that I painted later, but he proved to me the soundness of Andy Evans' advice.

At any rate, check out Andy's examples and methods. They can be applied to any camouflage pattern.
HTH,