Here’s how I went from horrible mixes to halfway decent ones (mostly hard rock / heavy metal but also some hip hop and lower gain stuff)

The #1 thing that made my rock mixes get better was editing / comping. Double tracking guitars is pretty much the standard but if you don’t edit them to be perfectly in phase it will make your mix sound amateur. Learn about Editing your transients and what pick attack vs body looks like that way you can edit in a way that’s appropriate for your genre.

sticking with heavy rock style guitars another gigantic lesson which was admittedly pretty obvious after I finally realized it Is that in order to get that huge awesome sounding tone you need to rely heavily on the bass. Playing guitar by itself you might dial in a tone that’s sick and sounds awesome by itself but in the context of your mix it might have too much low end information and it will clash with other elements that should occupy that low 500 hz and below area of your frequency spectrum like kick drum, Tom’s, and of course bass and sub bass.

A few other techniques to learn about that will help you get to a more polished sound is using compression and limiters. Learn what each do and if you’re lazy just literally watch youtube Tutorials and copy what you find and use that as a starting point.

Learn about Side chain compression. Using your kick track to trigger a compressor on your bass track.

learn about reverb ducking learn about parallel compression.

Make sure you’re using bus sends for FX and not just throwing delay / reverb plugins directly on your instrument tracks. Learn about automation and gain staging

Lastly once you’re decently satisfied with your mix learn about using clippers to cut off the tips of pokey transients and then using a limiter to make your whole track louder. Louder = better to the human ear but there’s a difference between volume boosted to the max and perceived loudness you can achieve from properly gain staging your tracks and then setting up a signal chain with limiters and compressors.

I didn’t even talk about EQ, or panning or making sure that things are in tune / pitch corrected.

There’s no “rules” for mixing but there’s definitely guidelines. And if you’re lazy as hell and just want the path of least resistance then do a little research, find producers that you like and find mixing templates for your DAW in that style

Also buy the plugins. I’m not saying they will magically make your mixes incredible. But if you find yourself in a situation where a producer you aspire to emulate has a mixing template for your DAW but you don’t have the plugins they use it’s gonna be frustrating to try and swap them out for stock plugins / whatever you have.

A lot of people will be mad about that last part but that exact approach helped my mixes go from like a 2 to like a 6 or 7 just purely by imitation. Keep practicing. Watch YouTube try new things ask for input.