The Compressor Pedal is one of the most misunderstood pedals out there. There are many ways to use a compressor effectively. I use mine as an always on device that makes my sound really come alive.
A compressor will help even out your sound by bringing out the soft parts and bringing down the loud parts. This will help with clean sustain by bringing up the level as you notes start to fade. You will get a more consistent sound using a compressor this way.
You can use the compressor as more of an effect by turning up the compression level to get more of a “squished” sound. This is great for Chicken Pickin’ country guitar as well as for Funk gitar parts.
You also can use the Compressor for a volume boost by turning up the volume control and turning it on when you need a little more volume.
The Compressor can be a very subtle effect, one of those effects that you don’t notice until it’s not there.