I use the avatar movement method, here's what I do (sorry for cross-posting this, I have it on another thread, but it seems appropriate here):
Add or subtract 1 foot for each inch the putt goes uphill or downhill.
Take that number and divide by
Slow Green divide by .9
Standard divide by 1.0
Fast divide by 1.1
Very Fast divide by 1.2
Tournament divide by 1.3
And use that number as your putting distance.
Figure out how many movements the avatar makes (draws back the putter) for your putting scales. For example a 15' meter has 2.5 movements so the first two are 6' and the last is 3'. A 30' meter has 5 movements of 6'. A 60' has 5 movements of 12'. Divide the length of the putt (the number you figured above) by one movement, i.e. a 23' putt would be 23/6 = 3.8 movements on the 30' meter and 23/12 = 1.9 movements on the 60' meter. Move the avatar the appropriate amount. Sure, if you come up with you have to move the avatar 2.73 movements it's not going to be absolutely clear how far to move it unless you tape something to the screen, just as you would have to do with say 73.5% using the percentage method, but I don't do that.
One more thing: on the last avatar movement, "waggle" it a little (move the putter back and forth) to "dial in" that distance. Then move it to where you want, i.e. if it's 1.8 movements you want, go to the second movement, waggle, then back off a bit. If it's 3.3 you want, go to the third movement, waggle, then add a little more.
And of course inside of 10' you're going to want to hit it a little harder than the number you come up with and inside of 3' you can usually ram it in.
It's easier than it sounds.
I almost always get the distance right, misses are not reading the break as well as I should or missing the ding by more than I should.
Source for formula: http://www.wgt.com/forums/p/89159/565243.aspx#565243
Source for how to waggle: http://www.wgt.com/forums/p/22186/127277.aspx#127277