Having just attended the Ray Daniels presentation on serving draft beer at the NHC, I learned much about serving beer from a keg.
The 2 big variables are temperature and gas hose size and length, (he recommends long 3/16 not 1/4). The goal is to pressurize the keg at
about 4 PSI above the internal pressure of the keg. (not to just 4 PSI like we have been led to believe) Since, the temperature of the beer
has everything to do with the internal pressure inside the keg there is big difference between beer served at 33 vs 50 degrees.
It is very interesting that if you fall out of that sweet spot both high or low the results will be the same a overly foamy beer.
I would suggest you look at he presentation when it's posted on the NHC web site.
The real take away is to use long hoses at 10 to 14 PSI, start at 14 as the beer warms up you will need to start decreasing the PSI.