I think you have to start by asking yourself what you would like to create. Design is nothing in itself, it’s a component of creating something. For me it started with a passion of creating interactive documentaries, and generally making content online more immersive than just plain old text.
Once you are there start looking for inspiration a bunch of places. It does not have to be apps or websites it can also be magazines, movies, commercials etc. How is the use of colors, fonts, images etc creating an identity. And what kind of journey are you invited to take, and how is the invitation presented.
A good starting point can be to simply copy things you find great. Copying is a great way of deconstructing things to figure out how they work. Once you start to understand, you can add your own tweaks to what you copy, and in the end it will start to be more yours than the vision of someone else.
Here is a couple of examples of projects that inspired me (and on the last slide is a clip from my first project The Enemy Within: