BSA vs. Nonfat dry milk for serine/threonine phosphorylation sites - which is better for quality blots? (Mar/27/2008 )

So I am working with many different phosphorylated antibodies that phosphorylate different sites at serine/threonine residues. I know for phospho-tyrosine sites BSA blocking is much better but what about these residues? Also, if I block with BSA does the primary and secondary antibody have to be in BSA or milk or some variation of these? And what about percentages? Everyone seems to have different opinions and techniques, I am curious to hear what anyone has to say on the topic. I dont really know if there is a wrong answer, just better ones. Thanks!

In case of phoshoproteins study milk isnot recommened as a blocking as milk contains casein which is a phosphoprotein and it will cause a very high background as the phospho-antibody detect it in the milk so its better to use 3%BSA in 1X TBST as blocking buffer and base for diluting first and second antibodies.