You should pick soft triquetrous pencils for a small kid. It is sufficient to have a set of six basic colors. When coloring, try pronouncing the name of each color, this helps the baby to remember them.
When painting figures (for example, from 1 to 10) it develops a color perception, fine motor skills, attention, diligence and accuracy, mathematical ability. Such tasks are connected to the process logic of painting, allow to fix the basic math skills or letters.