There are way too many combinations of factors for us to give you accurate advice. The power and speed needs can change from day to day and definitely can change from one piece of wood to another. With enough experience, you will be able to get your settings very close on the first try.
+1 to material test - the only way to learn how is to try and make mistakes, then you correct the mistakes and get a better result. There is no shortcut in the game.
Please keep in mind that “cutting” and “engraving” are two ends of the same string.