CharlesPapert
Director of Photography
One suggestion I would make, is to use sunlight whenever possible. Go to whatever lengths you have to and bounce real sunlight from windows etc. This will make a HUGE impact on what looks slightly more "filmic" and what appears a bit more "digital". Like others have said it's just a buzz word, however there are some innate qualities of celluloid, that seem to translate over to digital now and again in the right circumstances. Most digital video under tungsten lighting comes off as just regular HD video most of the time... it's hard to escape that look. Even that trailer for Upstream Color that was posted above... hardly used any artificial lighting except as an accent. The film looked absolutely stunning in the theater and really "felt" like a film, rather than a film shot on video. The main reason overall, was that they used sunlight and molded it to get their look.
I'm not advocating to not use lighting... just that you try and incorporate real sunlight whenever possible.
The only way I can begin to agree with any of this is if it is limited to those who are not experienced or talented enough to be able to light properly from scratch, or lacking the proper resources. Natural light is beautiful but a good DP can recreate it to a degree that few if any could detect the difference, given the right tools/time/crew. Given that one may be shooting a scene that takes place in a matter of minutes on-screen but will take hours to shoot, relying on natural light requires a significant amount of planning and discipline to be able to maintain visual continuity throughout.