| One thing I do agree with is the Emily Post advice.  I find that the more I try to explain WHY I say no, the more people take that as an invitation to decide that my priorities are wrong and get annoyed.  I try (as much as is practical) to say, "I'm so sorry, I can't," rather than detail out why. 
				__________________'He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me.' 
-TJ
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