I mostly use pitch or punch shots out of sand, although flops do work sometimes - like on Bethpage. I simply double the extra hit amount for the equivalent rough percent. For example for 30-40 rough, I add 10% extra to the shot but for 30-40 sand, I use 20%. If I go with full back spin I would add another 5%, so 25% for 30-40 sand. Then for uphill shots out of sand I add 1 extra yard for each 3' of rise. Then, if you have enough green in front of you, remember to take off something for the extra roll out you will get out of the sand. For tourney greens I figure about 2-3 yards of roll out - again if I have enough green in front of the pin.
There are a lot of factors involved - sand percent, shot type used, amount of spin applied, amount of rise from the bunker to the green, green speed, amount of green in front of you and which course you are playing - as the sand performs differently on some courses.
For very difficult sand shots like 40-50 from 6-8' below the green don't be afraid to use a half strength full shot with a wedge if need be. C