Quite a complex subject, I wouldn't say I shoot for any particular RMS figure.
Actual RMS and perceived loudness are two different things in any case, spectral balance can make things sound louder even though it may not actually be measurably different from another song with the same RMS.
I just try and mix the song as best I can with plenty of headroom, bounce it down without any or perhaps a small amount of 2buss mix glue....then I can play with the loudness afterwards with some mastering plugins. I'm finding that different songs react quite differently, some will sound good at -8 , others will sound wrecked even at -10 or -11. Once I've finished I put it through the TT Loudness meter...if it comes up with less than -10 then I have a rest and go back to see if I can increase the dynamic range...most stuff I mix seems to come out between -13 to -10.
One thing I find useful is on Slate FGX is the 'Constant Gain Monitoring' button , which keeps the music at the same level , even in bypass. So you can check if it's really helping or you're just being fooled by the boost in level.
I have noticed this little Mixcube I got recently gets you to focus on the critical midrange, and if you can get it right on it then it actually does sound subjectively louder than if you'd scooped out the mids and made the mix too smooth, which I have a tendency to do
CD
We never finish a mix... we simply abandon them.
You can't polish a turd, but you can always spray paint it GOLD
Great songs are not written, they are re-witten