Hats come in an infinite variety of styles, from form-fitting, pull-on styles that firmly and securely stay in place, to precarious fascinator-style that may or may not utilize an elastic or ribbon strap, meant to be secured beneath the hair or under the chin. Some fascinator-style hats require the aid of a fastener, such as a hat pin, to stay in place. These types of fasteners have been used throughout history; in fact, hat and hair pins have been found at archeological sites that date back to ancient Greece and Rome.
Style your hair as desired, and place your hat on your head.
Remove the stopper from the pointy end of the hat pin, if necessary.
Look into the mirror and arrange the hat so it is angled as you'd like. Hold the hat in place with your non-dominant hand.
Pick up the hat pin with your dominant hand, and reach around the back of your head. Insert the hat pin through the back center of your hat, pushing into your hair. Stop pushing when you feel the pin near your scalp.
Re-angle the pin slightly so when you push, you push the pin back up through the crown of the hat.
Tug lightly on your hat with both hands to ensure it is secure. If not, remove hat pin and reposition it so that it catches more of your hair under the hat.
Cover the pointy end with the stopper, if included and desired.