Burgers are the most under-rated fare. I often order them out to see if the chef is any good. You can do so much with a burger, it is very exciting. Here are a few of my "rules":
1. Start with the beef. 80/20 ground chuck is the best. I have had so many people tell me about ground sirloin or lower fat ratios. I always arrange a blind taste test. 80/20 always wins over lower fat. Try it yourself. Of course if you add pork to the mix, which is a nice option, you've changed the rules and the fat content, but I'm talking purist ground beef here. Personally, I have no idea what ground round is good for. I just don't like the flavor of round steak, and I don't care for the drier burgers and flavor. The chuck has a good flavor. My grandmother made what I consider the best burgers. Her secret was to add a tablespoon of sour cream (not the low fat kind) to a pound of meat. This adds extra "juice" but it also melts away so the burger is not so hard packed. Many comments previously talk about overworking the meat and I fully agree. The sour cream is another way of getting this same effect in addition to increasing the moisture content, making cooking a bit more forgiving. Also, if you have radiated beef available to you, go for it! I prefer my meat rare, but with burgers this can be dangerous, so the really tricky part is to cook until done, but not dried out, which is the hardest part with burgers. I wish we had radiated beef here.
2. Add what you like. This is the exciting part. There are so many options. I've tried most of the ideas posted and I love them all! I like especially the Worcestershire sauce mixed in. Also, I do not mix all the spices in with the meat -- the flavor gets lost in this case. I prefer to add spices to each side of the patty before grilling. My standby is Lawry's, fresh ground pepper and parsley flakes.
3. Cooking: Again, I agree with most of the previous comments. Start with a very hot grill. When I put the burgers on, I turn the heat way down. You want to sear the outside and then cook slowly so the inside gets to temp. Of course if you have radiated beef, this isn't essential. The amount of time is the really tricky part. When the burger swells up, all the fat inside has been turned to juice and the burger most likely is overcooked and will be dried out by the time it hits the table. If you see a pool of juice on top of the burger, the same. You need to catch the burger before this happens, usually, when there is a nice sheen, but it has not started to swell. It really is an art and requires some practice. Also it is very dependent on your grill and the grilling conditions.
Man, I love burgers, and to answer chambersuac, it is ok to have burgers for breakfast. I've had them many times.