Howdy,
Over the last few years of serious tinkering with YASim, I've collected a volume of notes related to my experiences and findings. I've finally finished assembling these into something that is more-or-less readable. It's not quite complete, notably it's missing a section on landing gear and turboprops. But I think it's now worth a look, especially for those relatively new to YASim.
http://www.buckarooshangar.com/flightgear/yasimtut.html
Regrettably the guide does not include sections on rotary-wing aircraft. I try to write only about things I have first-hand experience with, and I've yet to work with YASim helicopters. My apologies to all the helicopter fans out there.
Constructive comments, suggestions, and other feedback are always welcome.
-Buck