Eq changes the relative strength of different frequency ranges.
Compression is like a very fast hand on the volume control that reacts to the level of the signal.
Reverb is like an artificial room or other space where the sound of your voice/instrument is multiplied/delayed/filtered then added back to the original.
There are many different, and conflicting, "right" ways to use those tools, all depending on the source and the user's goals and preferences. It takes time not just to learn generically how to use those tools but to develop your own set of preferences and procedures. Users tend to fall into one or another of several different styles of use, but it's not a precise science. It's that imprecision personal preference that makes it hard to tell you what to do or not do.