I'm not really just meaning one thing, I just totally can't grasp mixing at all. Showing samples wouldn't really help because it's not just about one thing... but here's a short teaser track I just did yesterday anyway. I guess I can point out a few issues.
https://soundcloud.com/uoyssimi-niar/cumulonimbus
It's probably gonna sound like arse on your side. But anyway, take note of a few things.
The track is totally clipping, I just slapped on a sausage fattener (which also has limiting) and a limiter before exporting, and I know that's not the way to go.
At the intro itself, you can hear a deep thump every 4 bars. There's only like 4 layers, 1 strings, 1 piano, 1 bells and that thump. Yet it's already clipping. And that's after reducing the volume. I'd prefer the thump to peak at 0db. Even now after so many reductions, it still clips 0.24db for like 0.5 seconds. I have no idea how to identify what's the frequencies, and even if I do, isn't it really dumb to cut out frequencies just for pops here n there?
When the war drums come in, same issue. It's quite perfect, there's only 3 layers after all. Piano + Bells, no lower frequencies to really clash. Then suddenly, at the part where there's 3 booms together, it clips at 1.79db for like 0.1 second on the third boom. I don't understand why it would considering I haven't added any elements or increased the volume of anything.
And now the EDM part comes in, and total mayhem. It's not even as loud as commercial EDM tracks. I've already set the volume way down. The supersaw + kick together alone is peaking like no one's business. So I'm ducking the kick with sidechain at the first verse. I take a EQ and high cut it starting from 800hz and it no longer really peaks. But that's of course ridiculous as it takes away like 80% of the sound. I can't even make 2 layers not peak. I have no idea what I'm doing.
...and that's just the tip of the ice berg of all my mixing confusion.