Hey MN friend! I used to live in St. Cloud but now im in Canada, but hey anyway!
There is not hard and fast rule about this. the best way to determined what needs to be compressed is to understand what the compressor can do for you (transient processing, dynamics control, sidechaining, etc.) and decide if you want to apply those things to change your sound. Every time you put a compressor on, use the "gain" control on the compressor so that you can equalize the peak level of the input/output. then A/B the compressor (like listen to the sound with the comp on/off) and do a blind test so you can determine if you like the sound better w or w/o compression. If you cant tell the difference, tweak the settings or just leave it off. only leave it on if you know you can hear the difference and you like it better with it on. be sure to listen in the context of the whole mix.
One more tip: I used to use all different compressors becuase i could download them free etc, but now imo its better to just pick a good one and pay for it (or use the native one with your DAW and save CPU) and stick with using that one so you learn ALL its functions. then your theoretical knowledge will improve and you will be more effective with a compressor rather than just laying them on blindly. I use to just strap em across everythign and it sounded shit.
anyway, most important just use yer ears! tweak the knobs in all directions and try to understand!
oh and have fun. and enjoy MN winters becuase they are a blessing. we have shit winters in this place honestly. Rain all the time. snow is much better you are lucky
