Tip #2 when buying a hat:
"Always stand up when you are buying a hat. Many's the lady who, framed in the little square mirror, looks charmingly proportioned, only to find, when she rises that she looks either pinheaded, or top-heavy. Never buy a hat the day you are experimenting with a new coiffure. You'll end up throwing them both away!"
Good advice, and one I would suggest when buying jewelry or belts too. It's important to see how your accessories look when compared to your entire body in a full length mirror. And take dramatic changes in small steps. If you're not used to wearing a hat, be sure it works with your current hair style before buying.
The hat above features red roses on a black and white striped base with an alluring spotted siren veil. By Walter Florell, January 1941.