lighting - this is the most commonly overlooked, and often the easiest to fix; use/buy more/better lighting!
lensing - be sure you select a good quality lens (a good lens is more expensive but passes light better), and that the aperture is open as far as possible (unless you have depth of field issues)
exposure duration - as long as possible relative to framerate desired or to prevent blurring if motion involved
use of gain - this should be a last resort as "noise" increases with gain... but slight use of gain can be helpful under marginal lighting conditions
Great! Indeed, by default Gain is "off". If autogain gets you an acceptable image quality, then that's what counts. Just know that image artifacts like graininess or flecking can arise if too much gain is used... which is why I suggested the lighting is the preferred way to get better saturation.
