Cooking a steak isn't difficult if you know a couple of things. First, you must know what cuts make good steaks. They are many, but each requires a different method for cooking. For instance, a flank steak produces a wonderful meal but should be cooked to no more than medium rare (very pink inside) and then sliced thin agains the grain and at an angle (on the bias). By cutting against the grain, you take a fairly tough cut of meat and make it more tender. A great bone-in rib steak needs to be cooked between rare and medium rare to allow teh full flavor of the meat to come through. The meat should be well marbled with flecks of fat all over the place, but with few chunks of fat. This insures that the meat will have full flavor and will be juciy and tender. For a chcuk steak, look at the steak. You will recognize three seperte muscles in this cut. The largest of these offers the most tender eating. The chuck is full flavored, but can be tough. The smaller muscles should be cut away and researved for stews and such.
There are a host of beef cut charts available for free on the internet. Simply type in Beef Charts on Google and you will find full color charts of the carcass telling which cuts come from where, and the best ways to cook them.
Also, know that in order of quality, in the U.S. are prime (don't worry, you won't find this at your local supermarket), Choice (the best you can get at your local supermarket), select (the lowest grade you should ever purchase), and down from there. You usually won't find anything less than select grade at your local market. Select is what you purchace when you want to grind your own ground beef. It has larger chunks of fat and less marbling. It is tougher, and less flavorfull than is Choice-grade.
As for technique, many of us have favorite techniques. And there is no "perfect" way to cook a steak. But the favored methods all share some basic principles. These include cooking to the proper degree of doneness, avoid piercing a cooking steak, fiddle with the thing as little as possible, know your equipment. Surprizingly, both gas and charcoal can give excellent results. Often, people who have been given blind taste tests couldn't tell the difference. I prefer a charcoal grill only because I can do things with it that I can't replicate on a gas grill. But cooking steaks isn't one of them.
Tell us what cuts you will be cooking and we can give you a host of techniques that will give you great end results.
Seeeeeeya; Goodweed of the North