Mixing priority is very important. Dale North taught me the basics of this ages ago, and I owe him hugely for it. I use this literally EVERY time I mix music.
Pull all your faders down to 0. We’re going to create a solid “static mix” (no automation) one instrument at a time.
Start with the drums. Bring the kit up to about 70%-75% on the fader so you have some headroom. Adjust your speakers so the drums are a good, comfortable volume.
Next is bass. Bring up the bass instrument until it’s nice and clear, and works well with the kick drum to push some air, but doesn’t mask or overpower the kick.
Now bring up the “lead” instruments like vocals, guitar solos, or whatever instrument is playing the melody. You want the leads to be roughly the same volume as the bass, maybe a bit louder. The finer points are very subjective, but your goal here is that the leads should be clear, and sound like they’re being supported by the foundation provided by the percussion and bass, but not like they’re overshadowing that foundation. A note about reverb here: less is usually better. Remember, these are the LEAD instruments. Would you put the lead instrument four miles behind the band in a live performance? Use reverb to create depth, not to swallow the track. If you ARE using reverb as an artistic effect, try using minimal early reflections with a long tail at a lower level. You’ll get the “cathedral” effect, but won’t wash out the presence of the original signal as much.
As it sits now, your mix is giving the listener the most important elements. They can hear the beat. The low end is present. The melodies are clear. At this point, you’ve got everything you NEED. Everything else that happens should always enhance what you have here, and not obscure or otherwise damage it.
The next things to bring in are rhythmic backing instruments like guitars, piano, brass section, etc. Start bringing each one up until you like the way it fits in the mix. Also try panning these instruments around to create width if you like. You can also use reverb to move things around spatially. And if a track feels like it’s fighting with with one of your core elements from before, try using some EQ to create some room by reducing the volume of the offending frequency range. Remember, if a track sounds great all by itself with a glorious reverb and a nice full sound, it probably won’t play nice when you sit it in a mix. If you treat it like a lead, it will try to stick out like a lead. Your chord/rhythm instruments need to serve the groove and help add to the foundation for the leads. They do not need to sound good by themselves.
If you have slower, “pad” instruments like string or synth swells, or other ambient sounds, now is the time to bring them in. These will usually need the most panning, reverb, and EQ, and will usually be lower in the mix than you probably expected them to be when you recorded them. That’s OK. Remember what they are there to add, and make sure they add the colors you want without turning the mix into mud.
The last thing to bring up are any “sparkly” or “accent” sounds. Those wind chimes that only hit four times in the third chorus, but nowhere else in the song. Or the little synth bleeps that fill in the holes in the groove here and there. Bring them up until you can JUST hear them, and see how they work in the mix. Pan them around. Add reverb or echo. Make sure they’re present enough to be heard and contribute to the mix, but (as if I haven’t hammered this in enough) make sure they aren’t interfering with anything else.
At this point, you should have a good, workable mix. You may even be DONE mixing, depending on how complex the arrangement is. Give the static mix a few listens and some time so you can identify any areas that could benefit from some movement. Maybe the piano is perfect in the first verse, but on the second verse, you’d like it to come down a bit so you can push the groove more with the guitars. There are any number of similar subtle (or less-than-subtle) tweaks and adjustments you can make later using automation now that you have a good static mix to use as a starting point.