There are 4 most important things to remember while choosing paints are: the type, the form, the quality and the color.
Watercolor comes in two types:
• The transparent pigments
• Concentrated dyes.
Fine artists and professionals mostly use the transparent watercolor pigments where as concentrated watercolors are commonly used for illustrations and architectural drawings.
Pigment colors are more flexible and can be manipulated easily compared to concentrated colors. Concentrated colors are brighter and cleaner and actually stain the paper surface. They can be manipulated only while the color is moist on paper.
These are available in watercolor tubes, and pans / dry cakes. Most of the artists prefer to use Pans as it comes in set of all colors in a self-containing box. This is easier to carry for outdoor paintings and the covering lid of the box itself can be used as mixing pallet.
There is a wide variety of Watercolor pencils available in market. These are easy to carry and can be used in similar way as normal pencil colors. These pencils are made of water-soluble color leads that give similar effect as watercolor pans. This medium is little tricky because water is applied after drawing with pencils is done.