Hi,
I use only Vallejo colors that are the same as Andreas only with a different brand name.
I always use Humbrol's flat gray nr.1 as a primer.
To shade and highlight your model you have to lay several coats of color in varying tones, you can neither blend them like oils nor drybrsh them like enamels.
After practising a bit I piked these colors because they have a wonderful flat finish and they are water based so I don't have to inhale toxic vapours from paints and solvents.
If you have a look at my site Braveheart is the last figure I've done with enamels and the Highland Regiment soldier is the last one I've made with acrylics. To me they are of the same quality (in painting).