Experimenting with colour

I've been exploring different techniques for painting my 15mm vehicles. I'm looking for a process that is both quick and effective. I don't want to spend huge amounts of time painting game pieces but I do want cool looking models when I'm finished. I've never done 15mm before so I appreciate that the techniques for a successful miniature will be a little different from a 28mm mini for example. I've therefore decided to experiment with differing styles on similar models (my Stug G's) to see which method I prefer. The first tank was given two drybrushed coats of Middlestone (Vallejo 882) while the second was base coated in solid color (picture above). I then used a wash of black (1:10) to bring out the detail on the second model. I'm still unsure which method I prefer and need to experiment further.

The other experiment I tried was how to get the camouflage pattern right. I painted a blank patch of Middlestone and tested different methods for applying the two colours (Chocolate Brown 872 and Reflective Green 890). I don't have an airbrush (yet) so I'm looking for a technique that will produce soft edges. Battlefront's painting periodical, The Art of War (Issue 2), suggests a watered down technique applied in multiple layers. However I found the paint pooled too much and left a 'tide mark' around the outside edge. So I tried it again diluting the paint using my 'special water' (Water & Flow Improver 1:4) but again it didn't have the soft outline I wanted. So I made a third mix, this time with the paint diluted about 4:1 with stronger water mix (This time 50% flow improver). Disaster! Far too much flow improver and the paint just spread across the surface uncontrollably.
Back to the drawing board. This time I reverted to my regular 1:4 water mix and applied one part paint to 2 parts my special water (1:2). This looked better but still not quite where I wanted it. The final test produced the best results with a 3:1 ratio of Special Water to Paint. The resultant patch was soft edged and slightly opaque. It's not as good as airbrushing but it might be a suitable alternative.

Having played around for a couple of hours its now time for me to hit the forums and see if anyone else has a better technique.