[yummypaint]

Check out James Bruton's excelent youtube channel https://www.youtube.com/c/jamesbruton/videos

The general process he uses in his projects is worth emulating, as well as many of his design choices. He also provides 3d print files and code.

As far as a specific project that would be a good entry point, I reccommend making some variety of inverted pendulum which is actively balanced by a microcontroller. Every skill needed to achieve this is fundamental to succeeding and having fun in robotics.