We know we should use compressors but much too often, especially if you're new to mixing and playing around with compressors, we are confused a bit on how to set them up properly.
What exactly do the knobs do? How much of this or that should I use and why? Most of the time and especially if you're doing it right, it should be very hard to actually "hear" a difference, unlike when you adjust the knobs on a reverb plug where you CAN actually hear an immediate difference. Because we can't hear the differences in many cases, we guess and run blindly into the process hoping we're somehow getting it right...or at least close. Sound familiar?
So... here's a link that explains the functions in a basic way to get you started in the right direction with compressors, or perhaps, get you back on course.
How To Use Compression The article also addresses 5 common problems in a mix and how to use a compressor to "solve" them.