I couldn’t listen to the clip but here’s how I improved my mixes by about a million percent:
On your master, load up a spectrum analyser and an oscilloscope (my faves are Seven Phases Analyzer and s(M)exoscope).
Add an audio track with a reference track. Anything that’s in the same style as your tune and that’s mixed well will work. Set the audio track to about -6 to -10 dB. It’s likely mixed well and mastered for loudness, and we want our final mix before we use a limiter to end up at about -6).
Turn down all of your own tracks, and start turning them up one by one, and try to make them match the approximate levels of the reference track on the spectrum analyser. The order in which you turn them up is basically most important to least important, or as far as the frequency spectrum goes, most energy/loudest to least energy/quietest. Start with kick and bass, then drums, then synths, etc. Make sure the total mix doesn’t consistently hit above -6dB. You’ll take care of incidental transients and peaks later.
Then, solo every track and analyse what it needs. Focus on EQ, compression and saturation/limiting. Keep an eye on the analyser / reference track. Use the oscilloscope at this stage to look for big transients and tame those with compression, limiting, or my favourite, saturation. Fewer transients = more room to turn up your entire mix later.
EQ rule number one is high pass/low cut everything so that all unnecessary low end is gone. Try not to overdo this. Use your ears to look for any big timbre changes and adjust the severity of your cut accordingly. Use EQ to make space in certain elements for other elements to come through: every element should have its own place in the spectrum, within reason. Don’t let that principle ruin the quality or timbre of your individual sounds too much. Try to cut rather than boost when mixing on a technical level. If you do boost, try and use broad curves.
Use compression to even out the dB levels of your tracks. Even dB levels = more room for loudness later on. Don’t use compression just because. Only use it when you think it’ll do something, and try not to overdo it.
Put a limiter at the end and use it to turn up the mix as loud as you can until it starts to catch any rogue peaks. As soon as the mix starts sounding squashed, go easier on the limiter. Render the final mix slightly under 0 dB (-0.3 or something should work, most limiters offer an exact output setting) to prevent artifacts when converting it to mp3.
Always A/B with one or more reference tracks. Focus on space and clarity rather than loudness and loudness will come eventually.
Hope this helps.
P.S. Keep your low end mono. The kick and sub especially. If you have layered stuff, or your bass comes from a patch that has mids and highs, or when you have a nice stereo kick, either split those up into bands or use a plug in (like ableton’s Utility) to mono everything below a certain frequency.