Practice, practice, practice!
And, like everyone else has mentioned, brine it, and don't overcook!
Brining is the easy part. I brine all chicken that gets grilled, smoked, or roasted. I brine turkey as well.
The second half is not overcooking the birds. That comes with practice. I can usually perfectly grill chicken, and just poke it to see if it's done. If in doubt, use a probe thermometer. 165 degrees F is the magic temp for all chicken except smoked.
Peace, Love, and Vegetable Rights!
Eat Meat and Save the Plants!