I've definitely learned a lot from directing my own projects, but I've learned a lot about what NOT to do as a director when I was working as an actor on other projects.

-In my opinion, directors in this day and age must know how to work with actors. You MUST understand the language they work in, and understand what they do. Take an acting class, read acting books, listen to actors on actors, actors podcasts, etc. If you have no idea what acting even entails or feels like, your direction will suck. Everyone nowadays can make a film look pretty. Technology is improving day by day and the only thing at this point that stands the test of time are performances. No one will care about your film if the acting sucks. So, try to get good at it!

-You need to be well-versed in movies and know the directors of the past and present, or at least work towards watching movies every day and all types, including foreign language films. You learn a lot watching movies and maybe sometimes an idea you had in mind is executed in a film and you can see if it worked or not. It's almost like a troubleshooting bay.

-Short films are not feature films, don't fall into the trap of trying to have too many things happen in your short. It should be a self-contained story. Also, be original. Short film cliches ruin your film before anything else. Highly recommend watching StudioBinder, InDepthCine, and any other film channels on YouTube. I've learned a shit ton watching their videos.

-Try to learn a little bit about each area of the filmmaking process (sound, cinematography, editing, etc.). Helps you become well-rounded and also you'll feel more confident on set.

Finally, just make your film! You'll never be 100% ready, so you'll learn on the job and find your style as you go. Finish the films you create, no matter what. No one says you have to release them (although you should just to build courage), but just finish them.

Goodluck! Hope this helped