Quite simply put the fastest way to get better at mixing or songwriting is to just listen to music. Any music. All music. Listen to stuff you don’t normally listen to. Learn from it. Listen to how the song comes together. Listen for the hook. Check out the structure of the song. Listen for the way the bass sits in the mix or the relationship between the kick and bass.
I have the opportunity to meet many really amazing engineers at Sweetwater. The one thing I can clearly say they all have in common is that they all are actively listening to music all the time. Music from all kinds of different genres and sources. If you want to be better as a songwriter or engineer, you need to be an active listener.
Want a great way to do this legally and without spending much? Check out Noisetrade. You’ll thank me.