"I do not use the flash, I prefer to use natural light"How many times have you heard this phrase? :)
For those who want to know more about using the external flash, I published a review on Ciao.it a great flash, Mecablizt Metz 48 AF-1 , with some practical advice (also valid for Other models of flash) You can read it here
Mecablitz Metz 48 AF 1 digital - Flash hot-shoe clip-on
Happy reading ... and good light;)