I am not familiar with Hat etiquette I know:
Remove your hat for a lady, or someone in a position higher than you
Remove your hat indoors, like at church.
Match your hat to the suit you are wearing.
Hats off for the Pledge or National Anthem
Other than that, I only own 1 hat, and its my great grandfather's fedora, as he wanted one like Dick Tracy when the comics came out. I don't wear it often, as the only suit that matches it, is a winter suit, that I have to have taken in, since I lost weight.