Put the condiments on the bottom of the bun, not the top. Put things like onion & cheese on top.
Never put mustard on a burger, it doesn't belong.
Ketchup is for babies.
A nice perfectly cut thin slice of onion can't be beat.
A little horseradish mixed in with the meat is a nice touch.
A dash or more of worchestershire or teriyaki is good too.
Screw the 80/20 BS, 90/10 is great.
I will rarely get a restaurant burger with bacon, never at home. IMO it overpowers the burger. If I wanted a bacon sandwich I'd make one.