There are so many styles out there, it's quite confusing, shall I wear a hat with a brim, a fascinator (hatinator) or headpiece, all these styles are in the shops but which one suits you?
Many people are not used to wearing hats and therefore find the whole idea very daunting!
I think it depends on the occasion and also your role at the wedding, if you are the Mother of the Bride you have a good excuse to wear something where you will be the focus of the room, aside from the bride of course! If you are a wedding guest, focus on your outfit and think about what is the best headpiece for this outfit....for example a light floaty dress may go really well with a vintage style pillbox , a patterned dress may suit a headpiece incorporating all the colouts in the dress and a motif which ties in with your outfit.
Also try and think about how you will wear your hair, hair up usually suits a fascinator more than a hat with a brim, and long hair worn to one side will look gorgeous with a headpiece worn on the other side of the head.
There is also your frame and face shape to consider, someone who is petite will usually be swamped in a large hat and may look better with a neat, small percher style or a narrow brim.
My opinion is a wedding is the best place to express your style in an outfit where accessories including a headpiece really make a difference!