Starting to draw

Today I decided to start drawing! This may be a temporary endeavor, but what can you expect from a 16 year old? Does anyone have some specific suggestions on how I should go about learning to draw? Something quirky that could hold my attention would be cool, such as drawing every person that walks by in a park. I’m just looking for some kind of ritual that could get me into this. Anyway I drew this 5 minute sketch of my girlfriend and would like some critiques.