Drawings
You can draw at any time and anywhere. All you need is a pencil and a ground to draw on. And if you really want to become an artist, you should always be drawing inbetween. All the great artists I know have done that.
Much drawing gives you the security of shaping out any form in your paintings!
A basic course of 3 or 4 days in drawing is also very useful for any painter. Even that you are not going to be an expert, the simple knowledge about proportions, perspective and the light and shadow in a picture gives you a lot of self-confidence, when you trace out simple forms in paintings.
For beginners, a DINA 4 drawing pad and a pencil B 2 is best. The advanced user will try charcoal or drawing ink.
Scribblings with ink are also nice for beginners.
Here you see small ink scribblings on a lightly coloured ground that children of 9 or 10 have done in my arts lessons at school: “Miniatures”. Especially successful were Christmas cards done in that style: The children did small ink scribblings on white paper. Then they coloured them with water colour pencils and we stuck them onto a coloured cardboard. They really looked cute and very artistic!
You can also do small pieces of art like that in my studio. All the material is there. Maybe it is kind of relaxing exercise as a break from painting.