The short quick answer is, all your gain should be at your first stage, every device after that should be run at unity gain (the level out is the same as the level in).
The correct way is to know the maximum output of each device in the chain, for example a recording signal flow would be a microphone, the mixer, a compressor, eq and into the digital i/o of the recorder.
The microphone is an extremely low level, you would set the mixer channel fader to unity as well as the master fader, you would adjust the preamp gain of the channel input to the desired level 0dB lets say it is drums and sometimes it peaks at + 20dB the console clips at +20, the compressor clips at +24 so you would add 4 dB at the input of the compressor, you are only compressing 4dB on the peaks so the output would be +20 again, however the eq clips at +18 so you would need to reduce the level on the output of the compressor 2dB so that you do not clip the input of the eq. You boost a bunch of bass on the eq and now you are clipping the output of the eq so you must reduce the input of the eq so that you stop clipping the output. Finally it is feeding a digital I/O that can only take +14 levels so you will have to reduce the output of the eq 4 dB.
In this way everything in the signal flow clips at the same time and you are not overlooking clipping in the middle of the chain.
On home equipment this is harder to find the maximum input and output of each device if it is even specified.
If you still have a CD player an easy way would be to adjust the level of the device so that it as never louder then the the CD player level. Hopefully everything else in the chain is designed to handle that level.
Now if you listen at very low levels (I often do) you might reduce the gain so that your volume control is running more in the 50% to 70% range to give you finer control over the volume.
Most devices seem to slightly distorting at 100% so I generally only run them at 90% or lower to give them some headroom.