The next three adjustments I head for without fail are kind of all related in a way: contrast, brightness, and, where an LCD TV supports it, backlight adjustment. Getting the right balance between these three settings is absolutely fundamental to getting the right foundation for your picture.
As a general rule of thumb, what you're looking for is the best balance your screen can manage between taking out greyness from colours that should look black (reducing the brightness and/or backlight output); leaving enough brightness in the image to reproduce subtle details in dark picture areas; and not forcing the picture's dynamic range to be so extreme that it looks stressed, noisy and low on detail at its darkest and brightest extremities (contrast).
I'm not going to try and come up with some specific setting numbers for the brightness, contrast and backlight settings, though. Sorry. This is partly because, obviously, each TV has different ways/values for tweaking these key picture elements, and I can't go through every TV from ever brand. But also I'm very keen not to become totally proscriptive in this feature, telling you all exactly what settings you should use for a particular TV. For unlike some sites, we at TrustedReviews believe that the subjective part of watching a TV - personal taste, in other words - is hugely important to people's enjoyment.
So sticking with generalities, my experience is that contrast almost always has to be turned down from a TV's factory presets, usually to around two-thirds of its maximum value for LCD, or even a bit less for plasma.
If your room is very dark, you could even experiment with going lower than that for accuracy's sake - though the image may be starting to lose ‘punch' at this point. The brightness and backlight settings similarly need to be reduced from their factory preset levels.
To be fair, some TVs aren't too bad in this department; Samsung's LED backlit sets, for instance, have a relatively sensible 45 per cent of maximum starting point for brightness. But by the time you've got as much greyness out of dark scenes as you can without sacrificing all the picture's shadow detail, you might well find you've got the backlight running below a third of its maximum level, and brightness at around 40 per cent.
A final point to consider here is the dynamic contrast feature carried by most LCD and a few plasma TVs. The idea behind these is that the TV continually assesses the content of the picture you're watching, to see how bright or dark a shot is. And if it detects that a shot is predominantly dark, it will reduce the TV's light output in a bid to make blacks look less grey. Then, when it detects a scene that's brighter, it will up the light output again to give this scene more intensity.
Indeed, it's only thanks to these dynamic systems that LCD TVs are able to produce the sort of 100,000:1 contrast ratio figures we commonly see bandied around these days. Most LCDs only have a ‘native' contrast ratio (where dynamic contrast isn't used) of between 1000 and 2000:1.
In general, I'd advise you to leave a TV's dynamic contrast mode on - some TVs don't let you turn it off even if you want too. But some TVs simply have better dynamic contrast systems than others, so if you find that your TV's picture regularly seems to flicker, lose too much detail in dark areas or suffer ‘jumps' in brightness levels during dark scenes, either see if you can tone down the level at which the dynamic contrast system is working, or else turn the dynamic contrast control off completely and see if you're less bothered by the slight increase in greyness over black colours that will probably then appear.