Play the flute while rolling it away from you, directing the stream of air across the top of the hole and subsequently raising the pitch of the instrument.
Lower the pitch of the flute by doing the opposite; rolling the flute toward your lips so that the stream of air is directed down into the hole, creating a lower, deeper pitch.
Use the adjustable tuning slider if your particular wooden flute has one. While some flutes are simply carved out of one piece of wood, many have two or three sections. Pull the section with the mouthpiece
-- the sliding tuner -- out from the body of the flute in order to lower the pitch and push it in further to raise the pitch.
However, it should be noted that the air flow method in Steps 1 and 2 is more effective.
Check your new tuning settings using an electric tuner. This will ensure that any changes you have made, either to the flute or to your playing style, have had the desired effect.