There are lots of tools: pencils, markers, paint crayons. Each material has its own characteristics and advantages, promoting the development of specific skills. It is recommended to start with pencils.
In the process of painting you focus your attention on a subject that is at your fingertips. If you do it with enough concentration, it will ignore the extraneous noise, unpleasant thoughts and worries. This is a very useful skill that will be useful in situations where you need to briefly forget about your physical or emotional pain.