A master griller knows how to make a steak tender and juicy on the inside and cooked to perfection.  Once you've learned this skill, you can't "go out" for a better steak anywhere.

Choosing the right meat:
Don't skimp on the beef.  You want a cut of meat that is between an 1.5" and 2" thick, and well marbled.  Marbled means that there is some fat throughout the steak.  Rib-eye (bone in) is a good, basic grilling steak.  A step up from that would be T-Bone, which has a firm strip sirloin on one side of the bone and a small tenderloin on the other side.  And my favorite is Porterhouse, which has a nice flavorful sirloin strip and a tenderloin on the other.

Preparing the steak:
A meat rub will also enhance the flavor of the meat.  A good steak doesn't need any steak sauce.  Your local grocer should have a variety of meat rubs, but I suggest staying away from smoke flavored rubs.  Marinades can also enhance the steak's flavor but you need to be careful not to over-power the flavor.  A quick marinade is good, but in my opinion an overnight marinade will ruin a good steak.  My personal recommendation is to rub the meat with a good steak rub right after taking the steaks out of the fridge and let them sit.  You can make your own basic meat rub with just salt, pepper and powdered onion and garlic.  And don't grill a cold steak, you always want the meat to be room temperature before it hits the grill.  Grilling a cold steak will make it tough.

Cleaning the grill:
A lot of people will tell you to clean the grill before cooking a steak.  A well seasoned grill doesn't really need cleaning unless there is a lot of "crud" on it (like burnt sauce from last week's barbequed ribs).  If the grill has a lot of build up on it, you need to clean it.  Either take a brush to the grates or superheat the grill to clean it up before the steaks touch it.  You don't want chunks of last week's barbeque sauce clinging to your meat.  If the grill required cleaning, put a light coat of oil on it before grilling the steaks.

Charcoal grills:
Make sure the coals are very hot, about half-white.  You also want some smoke to be swirling around when the steaks hit the grates to add flavor.  If you're cooking over wood blocks, this won't be an issue.  A lot of grocers carry wood "replacements" for charcoal.  If you're using charcoal, then throw some wood chips on the coals before grilling. 

Gas grills:
Gas grills are are really convenient but the trade off is they're not as flavorful as charcoal.  If you are cooking on a gas grill, get some small wood chips from the store and wrap them in aluminum foil, and put that foil as close to the fire as you can get.  When the grill is between 600 and 700 degrees and the wood chips are smoking, you're ready to put the steaks on.

Turning the steaks:
When you toss the steaks on the hot grill, you'll hear a sizzle.  Searing the meat locks in the flavor on that side.  After a couple minutes, rotate the steaks (without flipping) 90 degrees and you'll get a good crosshatch grill mark.  When you begin to see juices forming at the top of the steak, its time to flip them.  Don't use forks to flip the steaks, you don't want to puncture them, only use tongs or a spatula. Your goal is to only flip the steaks once while cooking them. 

Finishing the steaks:
Depending on how you like the steak (rare, medium, well) will determine the amount of time on the flip side.  Rare steaks will be spongy, well done steaks will be firm.  Don't be afraid to cut them to check for doneness, you're going for flavor not appearance.  In a while you'll get to know your grill and it will become second nature.