My tip, for those just starting out, try to hit your approach to the middle of the green, not at the flag (compensating for wind, of course). On miss-hits, you're more likely to still land on the green and avoid hazards, specifically water - holes #6, #11 and #18 on Congressional come to mind. It's a good way to practice your putting too, and it's a lot easier to get the ball close enough for a par with a putt than with a flop from 30/40 sand or 40/50 rough, especially at Merion... those weeds around the greens are hard to get out of some times.
Once you get better at judging distances & winds, elevations & whatnot, then you can start aiming for the flag.
Kelsey =)