What is your intention in the mix?
Are you trying to control DYNAMICS or TONE?
DYNAMICS -compression can be used as a smart volume control.For light compression, use aa lower ratio of 2:1, and if you just want to catch the loudest peaks, use a higher ratio, 4:1 and set the release to 50 as a default. How you can adjust the threshold until you see a reduction around -3db. Now adjust the makeup gain to bring the overall volume back up. If something is loud, we perceive it to be closer.
TONE -on aa dialog track, if you increase the compression a lot, say -10db, then the tone changes to sound much more aggressive, like spitting the words out. (that is with the "attack" set to 15 or above). Move the attack back to 5, and the tone gets warmer, and more pleasant to listen to. The higher the attack, the brighter the tone becomes. Faster attack time adds thickness to a track. But it can also cause serious damage by chopping down important transients.