ADYTHEGOLFPRO:
How do you play Tournament Greens? What percentage should you take off your putts?
Take your total net distance, that's distance and + or - elevation and Divide by 1.3. On Very fast greens, Divide by 1.2, and on Fast greens, Divide by 1.1 I've been using this for quite a while now and it helps.
So, if your're 30 feet from the cup and have a +4 elevation... you would divide 34 ft. by 1.03 for a total of a 26 foot putt.