Hey thanks! Imo, mixing and mastering are the hardest steps. You can have a good sounding piece in your DAW, but rendering to mp3 format may butcher the quality of your song. I had to tone down the bass of this song because the mp3 version kept sounding very muddy- I still think I can do much better. I know I can improve loudness and cleanliness... It's all about training your auditory perception and tweaking your instruments.