From About.com

Grilling Times by Thickness

These times are total cooking times. Divide in half for each side. Times are approximate and will vary depending on the type of grill, fuel, weather conditions, etc..

1. Let your steak reach room temperature before grilling. Some people might tell you that this isn't necessary, however I feel that this helps grill your steak more evenly and faster.
2. Trim the steak of excess fat. Any strips of fat should be about 1/4" thick. Also cut through the fat strip about every 1 1/2". When grilling fat shrinks fast than the meat and it can cause your steaks to curl.
3. Season. I light brushing of olive oil, maybe some fresh cracked pepper is all you want. Seasoning is entirely up to you. Preheat the grill. Hot as it will go for a gas grill or a single layer of ashy white coals for a charcoal grill.
4. Oil the grate. An easy way to do this is to take a piece of trimmed fat, hold in tightly in a pair of tongs and rub it on the hot grate.
5. Grill. Place each steak on the grill for one minute. Turn and grill on the second side for an additional minute. Turn and rotate 45 degrees and grill for half the remaining cooking time. Turn again. If you do this right you will get a nice diamond pattern of grill marks.
6. Remove when done. I use the pressure test to check my steaks. When you are getting close to having a done steak press it with your index finger or the flat side of a grilling fork to get a feel for it. A rare steak will be soft. A medium steak will be firm but yielding. A well steak will be firm. Once you get the hang of this trick you will be able to remove steaks from the grill at just the right second.
7. Let the steaks rest for 5 minutes before serving. This will let the juices flow out from the center so the whole steak is nice and juicy.