For Python I used SoloLearn, an app on my phone during commutes. Took a month of standing room only T rides, but it made my time productive when I would otherwise been idle.
For Revit API via Python, most of what I know I learned by recreating, editing and reverse engineering the work of others. Early versions of Archi-lab from @Konrad_K_Sobon, Rhythm from @john_pierson and the lost but not forgotten DanEDU from @erfajo are some lost ‘educational staples’ from when I got my training wheels. Now @Andreas_Dieckmann’s clockwork package is still mostly in Python (and ever expanding), and the GeniusLoci by @Alban_de_Chasteigner is a more recent example.
Learning with an application is often ideal, but you will want to have a VERY simple goal in mind. Crawl before you to learn how to run and all that. I suggest you select something others have done and try to make it better by adding features or list looping to existing content.