You need to learn what all the dials on a preamp actually do theoretically and actually. The famous sticky is [[url=http://[/URL]="http://recording.or…"]here[/]="http://recording.or…"]here[/]. Fourth post down by Shotgun. Other than that you just need to practice spinning knobs with single purpose goals in mind like crunchy or soft or limit etc.

Maybe start with simple compressor technique, first.
This C6 six-band , just like the UAD Precision Multiband compressors, are racehorses and even seasoned engineers have to think twice once in while what they are doing.
Also, if you don't know multi band compressors well, you can produce more desaster then you do good with it. Multibands are NOT first choice in most mixing situations, anyway.

Watch [[url=http://[/URL]="http://www.uaudio.c…"]Precision Multiband Plug-In | Universal Audio[/]="http://www.uaudio.c…"]Precision Multiband Plug-In | Universal Audio[/]
It shows the features of good Multiband comp. But ignore the dude saying it would be an ideal tool for the novice, as well...
It is Not! Otoh, if you know it well, you could mix a song with it, not using any additional EQ.