My mixes sound so bad. Tips for good "sound"?

Hi all,

I’ve made great progress making some music but I came here to the forum for some more help because my songs have drums, keys and some bass. But the MIX is just plain bad. I put it on my phone to listen to my car and show my girlfriend but it doesn’t like “normal” songs that we’d hear on Spotify or in iTunes.

Any tips please for making them sound better. Like adding effects or finalizing them in a certain resolution. Or as a wav or mp3? No, there is no distortion in the master level.

Thanks all in advance!!!

Possibly* lack of dynamic range compression.

( * as you’re not linking to an example I’m just guessing )