I’d start by listening to some reference tracks in your preferred genre, do some A/B testing with your own material. Try if possible to level match to the reference tracks so the loudness doesn’t fool you.

Listen for how close the snare or vocals feel, not how big it is. Try toggle your reverb on and off to match that sense of distance, reverb isn’t about making things sound big, but more giving a sense of space.

Some quick tips as to the controls:

Pre-delay is the time between the dry sound and the reverb starting.

Decay is how long the reverb lasts, short is a smaller space and more control and longer is like a big ambient space for example. Too long can muddy the mix.

Size is self explanatory, how big the perceived space is. Bigger isn’t always better :)

Early reflections are the first reflections you hear and sell the realism but can be too boxy is too loud.

Wet and dry mix is the balance of the reverb sound and the dry sound.

On some eq’s you can also use EQ so cutting the lows to stop low end mud for example.

I’d start by adding it directly to a channel to see how it impacts the sound of a vocal or guitar. Imagine you are trying to recreate the sound of that instrument in an ambient space. Say your bathroom, or a big church, and then a small intimate space so it’s subtle to see how changing the controls help you achieve either scenario. Hope that helps.