While wearing a headpiece sets you apart from the crowd, there are a few etiquettes that you should follow:
Generally your fascinator or cocktail hat is designed to be worn on the right side of your head. This dates back to a time when gentlemen would be on a ladies left side, and the fascinator would not shield her face from him.
It is fun to stand out and make a statement, but do be cognistant of the occasion or event. If attending a wedding, you do not want to wear a piece that will distract from the bridal party or parents/family of the bridal party. You need to remember that this is their day, and you are their guest. It was fun to watch the guests for the wedding of the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex, but you'll want to make sure that you are elegant and are courteous of the other guests around (and behind) you.
Additionally, it is not advisable to wear a tall hat to a spectator sport or theatre production, again as you want to be sure that the person sitting behind you can also see.
Rules regarding time of day or type of dress
Most of all, just enjoy wearing your hat!
We just know inside that we're queens. And these are the crowns we wear. --Felecia McMillan