Ever tried mastering your own stuff but can't get it to the level that other people are mastering at?
It just doesn't sound right. It doesn't have any sort of feel; it doesn't sound finished. It's just kind of mastered, just louder. It doesn't sound like a commercial track. And the reason why I think that is happening is that you do not see mastering as a separate process, as its own thing.
When you're mixing, it's fine to mix into a limiter. That's absolutely fine, but make sure the limiter is at the end of the mix bus so that you can take it off then export it as a stereo file. You can export with the limiter on so you still have that reference point.
But you can put that limiter on later with mastering. The whole point of what I'm saying is you need to keep mastering as a separate thing. Bring the stereo file out, set up a new session. Start with mastering so that you're then putting the limiting on and you're going through your plugins, but you're thinking of it as mastering.
You need to reference against other tracks that you're trying to be against because that's how you'll get the level correct. That's how you can hear what's going on with the intricacies of the EQ, and you've left the rest of the process behind, and that's the whole point.
How I see most people go wrong is that they're trying to mix and master at the same time, trying to be the recording-mix-mastering guy.
The problem is, if you're building on it and start recording, and then build on, mix, and master – just adding and adding and adding – you're not really taking a step away from the process and just saying, "Okay, well, the recording's done, the mixing is done, and now I'm onto the mastering, and that's it."
Don't do it all on the same day, the same session, at the same time. Take the session out, leave it a day, or master it just as a separate thing. Go and have a cup of tea, come back. Listen to a few reference tracks to get you in the spirit of just listening to music, do that for half an hour.
Get yourself out of that mindset, so you come back to your mastering session fresh.