I work in gouache, an opaque watercolor, though I sometimes use pen and ink or pencils for line work, as in this study of lizards. Normally I work on a flexible watercolor board, which can be scanned easily for printing. For the occasional nonprinted work, I paint on rigid watercolor board.
Light can be a problem.
In my studio I use a basic fluorescent lamp with a daylight element built in to achieve the right color balance. Before I begin work on a painting, I create a calendar of what I expect to achieve, filling in the days one by one.