I put a bit too much effort into this one so I thought it might be worth a Steemit post. Some of these tips are basic mixing tips - but it goes without saying that if you don't have all of the basics down, you'll miss out on many important "cheats" that get a better mix.
Bear in mind that these are all suggestions and not all of them will work practically, but mixing is about experimenting to find how the right sounds fit together.
I'm also changing a lot of what I sent to my friend in the name of privacy, and to make this information a bit more generic. It's best to look at this article as a set of random tips.
Here it goes:
Guitars:
Firstly, reconsider why you're using fades at the beginning - it could sound like you've used this to cover up the fact that maybe the instruments don't come in all at once? You could think about just having a hard entrance.
Double tracking guitars is good, but less so if they sound like they've been DI'd - or at least mic'd from very close. It would be better to get a condenser microphone and record the guitar from a further distance. The sound of a guitar gathers around 1ft away but you may want to experiment with distance, and experiment with seeing if the guitar sounds better in the mix when the sound is being collected from in front of the sound hole, or from the body, or from the fingerboard (usually on top of the 12th fret.) If the guitar sounds too crisp and synthetic - it doesn't sound like a real guitar so it would be worth your time trying to see which mic position can get the best possible sound out of the guitar. This is a sound which is close to impossible to fix with post-processing alone.
Ensure lead guitars don't sound cluttered - especially if they don't perfectly line up with the chord tones that you're playing. That's not to mean you should strictly adhere to playing chord tones. No-one likes doing that and not many people know how to do that. You could just add a tiny bit of delay, reverb and/or saturation on these parts so that they "blend" with the rhythm guitar parts more and they'll fit together rather than sounding like two recordings on top of each other. This will also help them sound a bit different than the rhythm guitar, because it's pretty obvious if they're were recorded on the same guitar with the same micing/DI, and conceptually, if you were thinking of a live band playing this, it doesn't really make sense to the ear.
Another thing is that big electric guitar sounds need a bit of sparkle - this is possible with a bit of post processing. I don't fully have a problem with DI'ing an electric guitar but it depends on your philosophy as a performer/producer. I think this guitar sound has a tiny bit much distortion - instead of having a saturated sound it's more of a roar, which works great live but the concept of a recording changes how distortion is perceived. Lowering the distortion a bit would add a bit of brightness and clean it up a bit.
Drums:
If the drum sound is not up to scratch, I would recommend triggering or doubling the snare sound with a patch that would compliment the song, or re-recording it entirely. Alternatively, you could add a gated reverb sound onto it to give it more punch. Bear in mind, for some styles of music audiences prefer an authentic sound but sometimes triggering the snare sound is more effective than over-processing the snare sound you've already recorded.
(I later found out that the drum sound my friend used was entirely sequenced - it was just really difficult to hear in the mix. Depending on your recording philosophy, this can work, but you need to make sure you use a good patch - and really good sampled drums come with a price tag).
Kick and bass fidelity is one of the hardest things to get right and it would be worth your time to use a few reference tracks to see how the subs and bass work in commercial releases. They're usually where all of the power and feeling in a mix comes from. There are some things you could do:
Take a bit of sub from the kick (below 30 or 40hz, because the human ear can't hear these in a full mix context and people will rarely play the music loud enough to feel this)
Aggressively cut the mids/low mids on the kick, but keep the top in there. A good kick sound simply consists of subs to give the feeling and the click of the beater on the skin to give clarity. (A lot of the time you won't need this, but the further you record the kick from the beater, the more you'll need this mid-range scoop).
Side chain the kick to the bass, so that every time the kick hits the bass is compressed a little bit. This helps the kick come out over the bass more. (Don't be too aggressive with this).
Importantly: Remove subs and lows from every track that doesn't need them. Even bass doesn't need the subs to be that loud. With cymbals and high hats, you can be very aggressive with the low cut filter, so just the very tops come through.
Again, if you're finding it too hard to make the kick you've recorded stick through the mix, try recording the drum kit differently or sample replacing the kick. Again, this is better than over-processing the kick drum to the point that it doesn't sound real.
The bass guitar also needs tops for clarity. A lot of bass playing also comes from the sounds the player's fingers make on the strings. You can cut out the very tops but really, you get the punchiest bass sound from cutting some of the frequencies in the middle of the bass's range.
Usually cymbals are easy to mix because you have a lot of freedom, whether you want them louder or quieter, but you need to be aware if they're getting lost entirely or if they're so loud that it hurts when the song gets cranked.
Vocals:
I liked the vocal sound in this mix. Be careful if you have a limiter on the mastering bus or something because when the vocals come in the instrumental volume ducks (this might have something to do with Facebook or how you've exported it, but just know that when you send this to be mastered, the mastering engineer should handle the master compression and EQ).
(I later found out that this was that darn Facebook trickery).
Reference tracks:
Finally, the key to good mixing is to use reference tracks. Be sure to use contemporary ones, and try to find good quality independent works - not pop ones that were written, produced and mixed in a day. (Note: Many pop songs are worth using. "Uptown Funk" is considered the gold standard of reference tracks today). If your music doesn't fit in with a playlist of music that you want to sound like then it's not finished. Don't use artists like Smashing Pumpkins or Killing Heidi as references - their mixing is highly stylised. One I'd recommend is "Thank You and Sorry" by Maddy Jane. It's a local track but the mixing is properly decent, and it's a good example of electric drums used right.
Jake Long, who recorded the Maddy Jane track, is a real music nerd, so it would have taken him a big long afternoon to get a good electric drum sound. When in doubt, use real drums. But I won't criticise people's life choices.
If you release anything that's not completed because you want to pass it off as "stylised" then you'll regret it later on, because you'll find people won't easily want to pay attention to it. People are smart enough to tell the difference between "stylised" and "lazy", and you need to respect them for that. I think this song has potential and you guys have a lot of skill so don't short-sell yourselves with an incomplete mix.
That's what I did with my first "Nice Pie" EP. Don't Google it. Or do, because we sound better live.
Thanks, Steemit, for letting me nerd out. If you have any questions or debate-points, let me know