Stick it in a board mate! This once I'll do it for you:
It has two advantages by "beginner's opening principles": (i) it develops a piece (ii) you don't want to move the pawns in front of the King. But what about the variation I show? Bd6?! also obeys the principles of (i) not developing the Q too early, (ii) preparing to castle.
1.e4 e5 2.Nf3 Nc6 3.Bb4 a6 4.Bxc6 dxc6 5.0-0 Qf6
What is the advantage of this move over f6?