I am about 6'6" and have been playing golf since I was a kid. For me, the keys to consistent play have been:
1. Steady head -- do not let your head sway away from the target on the backswing! With a high center of gravity, it is really tough to recover from that position.
2. Bend over at the hips -- I have a tendency to stand a bit too upright, which results in a flatter shoulder turn and an over-the-top downswing. Bending over a bit more gets me in a more compact, powerful position.
3. Shorter backswing -- long arms are long levers! Lately I've been trying to feel as though I'm stopping my arm-swing at about 10 o'clock. No loss of distance, better downswing path and sequencing, and cleaner contact.