Thank you all for your usefull advices.

I'm using volume envelope for the backing band and of course in fade in or out.

I'm very carefull with EQ in the acoustic instruments, so I don't ruin their natural sound. I try to immitate a live act as far as possible, so I leave also the natural masking effect of overlapping sound sources, but also try to avoid it by separating them in sound picture in both the horizontal and depth dimension.

t all depends of the music genre: in some songs, where rhythm is important, I pan bass even 50% to left to bring it out.

I agree, that very often less is more: I at first take many real tracks from BB and then record with Reaper my own tracks. Then I very often build the song first muting most of the tracks and then adding and changing tracks. Even if I have recorded my own track for hours to get it right, I finally cut it out, if it doesn't fit the song, which is heartbraking.

But how about that placing of the sound sources in the depth direction in the sound picture? I learned from one of the greatest music recording expert in Finland, that delaying the backing instruments a bit (under 10 ms), brings out the solists, because then you hear them first. So it is in the live performances, where solits are in the front stage.
If it's a large area, they even use loudspeakerclusters far away from the stage overdelayd, so that it feels like the sound is coming from the stage, because you see the sound sources there, while the sound is actually coming from the closest loudspeaker. Psychoacustic is interesting, isn't it?

This is just my working process, which is build during the last six years, when retired I have had time to produce music at my modest home studio.

It helped, that I learned the basics of acoustics and electroacoustics, while I was founding and even the head of the sound and lighting department of the Theatre Academy of Finland in the end of the 1980s and co-wrote "Audiokirja" in Finnish, which they still use as a text book. Audio technology has developed since specially thanks to digital technology, but not so much in the electro acoustics. But mixing and mastering is new to me and I found this forum a very usefull to learn new tricks of the trade from you guys. So thaks again.