First off... I wouldn't go by the earlier posts in this thread. The game must've changed since March, because the ideas to play out of the sand around the greens are only marginally correct, IMHO.
It's really not that tough. Just think about it like real golf... watch where the club goes on the backswing for the distance you need. Yes - actually most often, it IS around 90% of the meter, but sometimes it's less - like around 65-75%. If your backswing is smooth (steady-paced), you'll notice the meter start to slow down as you reach the optimal shot strength. I usually go a little past that, and usually end-up around the hole. Pay attention to where you want to land it and the elevation change to that point on the green for the club choice, but still use the distance-to-the-hole for the shot strength.
BUT MOST IMPORTANT OF ALL... USE THE "FLOP" SHOT! Also, you MUST place your target well-left of the intended spot where you wish to land it! The wind doesn't come into play with such a short flop shot (usually... unless you're fighting a 20+mph cross-wind, or tail-wind). Naturally, placing the target depends on the slope of the green, as well. Start out (while practicing these shots) by aiming left a 1/2 grid. This means 1/2 of the entire grid, not a "grid square". ALWAYS hit the center line when playing any shot from the sand. The results of a mis-hit are very unforgiving!
Also, try not to take much sand with your shot. I always put the "spot" on the ball where the ball meets the sand and use the loft of the club to give the ball tragectory. However, I must say that I'm still experimenting with taking more and more sand, and trying to learn the appropriate strength for each shot as I do. I've found that "low juice" (backspin) seems to work best with the flop because this makes for very little roll after the ball lands on the green (depending on the slope and distance the ball "falls" from it's apex in the tragectory, of course). Believe me, I'm in the sand ALOT, because I try to get the ball close to the flag on my approach shots 9 times out of 10. Two or three out of those nine times, the shot is short or sometimes left/right which puts me in the bunker, but with the flop-shot in my arsenal, I don't sweat it.
This "technique" also works when "flopping" a shot out of rough around the green (out to about 33 yards for the Ping G10 pro set wedges - 54&60degree). I'm sure there will be varying levels of success with different clubs, but this will give you some idea of what can be accomplished.
As has been mentioned before, don't chip around the green unless you can use enough power to get the ball out of the rough/fringe on the fly. It will stop dead if it hits rough/fringe before it touches the green.
Bottom line: Practice! Try this out on some practice holes over and over until you see consistency, before taking it into a ranked round. And don't forget to convert yards to feet when judging how far the ball will roll after it hits the green. If you forget, your ball will undoubtedly roll past the cup (or come-up short) on the more demanding greens.
Good Luck! And by all means, post back your results after giving it some honest effort. I'm sure others, as well as myself, will be interested in hearing them.