My approach is to use Tamiya acrylic paints exclusively because they work so well with both undercoats and top coats. Undercoat thinned with lacquer thinner and top coat thinned with water. Here's an image of the technique on a recent AFV build of mine.
In this case, my base coat was Tamiya Hull Red thinned with lacquer thinner, for a good solid layer of paint. I then applied two
light mist coats of Tresemme aerosol hairspray. Avoid heavy coats of hairspray at all costs as it will lead to spidering of your top coat of paint and you'll end up removing large sheets of paint instead of small bits. Make sure it's an aerosol spray as the pump bottles will give you uneven coverage. When the mist coats were dry, I applied my top camouflage coat of Tamiya paint, this time thinned with water. When it was dry, I brushed water on the area from where I wanted to scrub away the paint. Not too heavy, as you don't want it to pool. After a minute or so to allow the water to loosen the top colour, I started lightly scrubbing away the top coat of paint with a stiff bristle brush. The tendency is to overdue the effect so be careful not to get carried away. Work slowly and check your results frequently.
Cheers,
Chris
P.S. I forgot to mention that I use Tamiya's flat paints.
