my experience is to check with the boat manufacturer and compare to what you have. An objective of propping is to control engine load so that the max mfg engine rpms are obtained. regardless of what is accomplished by tweeking propellers it all comes back to the engine.
tweeking has only to with increaseing the propeller efficiency while it is doing it's job. that said you can spend a ton of money chaseing margines particularly if your boat is near its hull speed. Truly, you can tweek to your crusing rpm which for a gas engine is 65 yo 70% of max rpm, very generally speaking. At least on diesels the fuel burn curve is predictable by the engine maker
i would grease the shafts where the prop slips on and make sure the shaft zincs are near a strut. on our stuff, we have the propeller hub taped so that a piece of metal can be placed over the end of the shaft with bolts passing thru which screw into the propeller hub as avery neat way to pull the propller off
I would suggest you read up on the relationship among diameter, pitch and cup