Use ISO's in multiples of 160, they're the native ISO's so they produce less noise. I would avoid using Cinestyle (on the 5D2 at least), if you're going to use a built-in picture style I generally use Faithful with sharpness at 0 (or 1 on Mark 3), Contrast at -2 and Saturation at -2. You don't want to have a super saturated image because it gets "burned in" and that's not ideal with compressed footage. I've been playing with Lightform picture styles recently and have been pretty pleased with the results.
Make sure all the noise reduction settings, Auto Lighting optimizer, and Highlight Tone Priority are OFF. Like the other guys mentioned, 1/50 shutter for 24FPS and 1/60 for 30FPS, so really the only settings you should be messing with are ISO and Aperture.
Also, try and get the white balance as close as possible from the get go, if you make large changes in post it can degrade the image. With video in general, try to get the shot as close as possible to how you want it and avoid "oh we can just add it/do it in post." I've seen some people take "does well in low-light" as "you don't need any lighting," which couldn't be further from the truth. Granted there are some situations that available light can work fine, but you're going to get a much better image if the scene is lit properly.
