The trick to cooking meat to perfection is watching it closely and allowing the meat to rest for 15 - 20 minutes after cooking to allow the juices to settle and reassimilate within the muscle fiber.
Cooking times can be tricky. For chicken breast I throw it in the oven at 350 for 18 minutes then hit the broiler for another 2 minutes. Once the chicken is out of the oven don't touch it for 15 - 20 minutes. Then dive in to the moistest meat your tongue will ever taste.
For steak, I take the steer out back, club her on the head, wipe her ass and put her on a plate. I like my beef blood raw.
If you are pan searing for medium, 3 minutes on each side with a resting period of 10 minutes will be perfect.