When mixing a track, go through every single track and sound. Inspect them using a spectrum analyzer.
Many times you will discover unnecessary low end (0-80hz) hum and rumble in pads, vocals, effects, etc. Clean that up!
It might feel like no big deal on a single track. But let’s say you have 20 tracks going on in a tune. Add up the low end rumble from all of those tracks and suddenly you have a pretty substantial blob of undefined bass noise going on.
So make sure to clean the low end – use a low cut EQ/filter to get rid of the stuff you don’t need.
Result: Your track will sound more defined, it will play louder and the bassline will come through much better.