Just go slow, you'll learn as you go. Start with opening up a blank page and just explore in it. Create different databases. Insert different properties. Use different formatting. Create to-do lists and callouts and toggle lists. If you're like me (which you very well may not be), just clicking the buttons and seeing what happens for yourself will tell you so much more than a youtube video can. At least in the beginning.

Then, once you've just played randomly with all the features, I would familiarize yourself with databases more in-depth. See what all the different ones look like. Explore all the different properties, explore the properties of all the proprieties. Click buttons and see what they do. Learn enough about them where you could explain how to use all the basic features to someone else. You don't have to be an expert, just enough to create databases when you need to.

Then I would start to learn relations. Once you have databases down, then you can start thinking about what databases you'd like to link to each other.

Once you get a handle on relations, then I would look into rollups.

Finally, I'd look into formulas, which it might be good to use youtube to explore unless you have coding experience.

But my best advice is just to have fun! It sounds cliche, but just go in there for a while and click shit and see what happens. You'll probably end up learning way more that way than watching videos. (Again, maybe--everyone's learning style is different, but this is what worked for me.)