There are lots of different opinions on this, but after making more than my fair share of homemade burgers, I have some thoughts to share. First, you should add some sort of bread crumbs to absorb the moisture from the meat as it cooks. I like to use panko breadcrumbs, which have a very light flavor that lets the meat shine. For flavor, I like to add shredded cheddar cheese, pickle juice (yes, really!), Worcestershire sauce, parsley, garlic powder, and simple salt and black pepper. The pickle brine will tenderize the meat and add a tanginess that balances the flavor of the beef. It's a simple combination that results in the most deliciously juicy grilled burgers every time!