Variable Pitch Props

I'm interested in learning about when and how to adjust the prop pitch in light aircraft and adapting the knowledge to my flightsimming .

I'm having a hard time finding any reading material online that describes how to use it and what effect on performance I should be looking for--what I should be "feeling" and listening for. Is it maximum RPMs?...Because I find the only effect I achieve as I advance the lever outward is reducing RPMs.

Also is there any relationship/coordination between prop pitch and fuel mixture.

Any knowledge you can share or guidance toward some useful reading is appreciated. Thanks