Ditto the above, but I stack 50 darks, 50 flats (for each filter)and 50 bias. I've heard some people taking as as many as 500 bias frames. I have a master library for every bin mode as well.
You want an average of the noise floor of your camera, so the more darks and bias frames you take the better your average, to a point. There comes a point adding more frames is not that benificial.
I'm no expert and I'm on the learning curve as well but this is what I've read from various places and it seems to work.
Read this it explains a lot
http://deepskystacker.free.fr/english/index.html
Its almost full moon so get cracking in your dark library