Quitting Valium

I have been on 15-20 mg of Diazepam for about five years.  I want to quit.  What is the safest and most effective way to do it?  It was prescribed by an aging Dr., whom I think will let me self-medicate in any way I am advised (swiching drugs at a decreasing dosage?).  I know tapering rather than "cold turkey" is probably advised.  But should I switch to a shortter acting benzodiazepine as a method? Some other class of drug? And what shoudl I expect for timing (length of withdrawl (withdrawal), weaning) cycle?  And what side effects should I anticipate as I quit?