Basic History
Water color came to western artists in the 1400s. Artist had to make their own paint and usually kept their recipes to themselves.  It was in the 18th century that a company started making water color paints for the general public. Paints would come in clumps that artist would have to ground up and water would be added.

Techniques
There are many techniques that can be use when painting with water colors. Below are some to the techniques.

* Controlled Wash
* Charging colors
* Softening Edges
* Lifting, Scrubbing, and Blotting
* Dry Brush, Wet-Into-Wet, and Salt
* Sponge, Graded Wash, and Splatter
Sources: Water Color Painting. Click on image for source.