Often though people will start providing more value without an agreement up front that it will earn a raise. In those cases a great boss might go ahead and give it to you spontaneously, but if that doesn't happen you need to know how to apply firm but friendly pressure.
Well, providing extra value without any kind of agreement as to what compensation you might get for it is, IMHO, a rookie mistake - and one you shouldn't make twice.
If you have confidence in your abilities, address the topic up front!
Often though people will start providing more value without an agreement up front that it will earn a raise. In those cases a great boss might go ahead and give it to you spontaneously, but if that doesn't happen you need to know how to apply firm but friendly pressure.