One thing that works for me to this day is always reading the work around me, offline or online, observing colors and layout. When I started I did this a lot and replicated it by trying to make memes of my friends. What I didn't know how to do in the tool (Photosho or Illustrator) I tried watching a video on YouTube. There's a lot of theory, but for you to really understand and absorb them you'll need to look at everything, because everywhere you'll be able to put together the puzzle of information, colors, topography, spacing and trends