Hi,
With alcohol the (water based) paint dries faster and sticks better to the underground. Sometmes I use very thin washes, which I blow with a haidryer to the remotest corners of a model or figure and can see the result within a few seconds.
When working with acrylics in a creamy consistance, the acolohol slighty disolves the paint underneath and mixes with it, resulting in very soft edges.
As Chris said, there are many styles of different painting techniques. Since I use my figures mainly on layouts, I try to get the message across for onlookers, maybe 3 - 5 feet away. So I have to exaggerate lighting and shading a bit, which often gives my figurs an expressionistic look when enlarged on the PC screen.
The metal figures in the samples were modelled after Carl Spitzweg characters. They are sold in some souvenir shop up and down the country.
Have fun
Fritz / Juergen