In my opinion, daily (or close to daily) practice is the most important thing.

Other commenters already cover which topics to go for, so I am just going to say this: If you do daily deliberate practice for a year, and whenever you are motivated research something with more depth from time to time...well, you will be somewhat good after doing this 365 times.

A bit shameless plug; I recently coded a small website which presents you with two daily changing images as drawing inspiration, maybe it will help you too: https://www.inspirationbot.art/