Well, I had this weird idea and so I started doing this little still project in Cycles. There is still some modelling and texturing to do, but for now I want to try and get the lighting right, which I’m having problems with. I was going for a gloomy, dark sci-fi look for the background and wanted some cliches like green light, but it all turned out too dark or too flat. However, what do think? Any advice? I’d appreciate it. 
cool, man. I was expecting to see a simple render of a modified phone, not a whole scene. 
looking good.
I think your scene would benefit from a different camera angle as well. I’m not sure what you’re trying to communicate the way it is now. Is it a sense of creepiness, or a silly sense of the robot imposing itself over the viewer? It looks like an action shot, but without any action. Pinning down the mood and defining what you want to communicate through your render will probably help you to find a lighting scenario that would better suit your scene.
I’m sorry if I’m only preaching to the choir. 
I hope that it helps. Maybe it would help you to study lighting in movies that you would like to mimic in this scene?
Thank you both for your replies. Since my last render just finished, I’ve attached it, but I’ve only changed some details.
I’m considering redoing the whole concept now, because I realise that my original idea doesn’t match what I came up with now. I wanted this iPhone from the future to convey something like “machines might take over our place”. But now my actual character turned out much too “comical”, cartoonish for this kind of background scene.
I’m not sure whether I should ditch the industrial setting and replace it with something brighter and cleaner; make the whole thing more like a cartoon. Or if I should try to go really extreme with the character and try to achieve something like the “matrix feel”. There’s a small hint into that direction with the dead human and the chains on the right side.
Which idea would you prefer?
If its about the iPhone taking over the universe then it’d probably be in the style of Apple… Clinical white white white…
The original image, I looked at it, then read, then realised I was supposed to have seen a phone, I didn’t. Yes its on the thirds, but its just part of the rest, not the focus 
Sounds pretty much like you’d want to borrow from some Matrix themes. But also, as someone else mentioned, if you’re aiming this at apple the clinical smooth white feel will be important too.
It all depends on what you want to do with the scene. Do you want it to be a scary visualization of what electronics could become in the future? If so, a Matrix type setup could work well. Or, if you want to downgrade the sci-fi aspect, you could move your phone into an urban household and bring your scene closer to home. There could be parallels with iRobot in that last respect, but all of these are just ideas.
Much better color palette by the way! Also, it’s hard to notice the person on the right. To downgrade the comic feel to this particular scene, perhaps you might want to consider laying dead bodies all over the floor in strategic places. And if you replace the joints with something that looks more practical and work on the legs to make them look less like a Tinkertoy, it would also probably help. Unless you want to size the robot down and bring it into someone’s household. Then the Tinkertoy feel could almost be believable. However, I think the machine your phone is using to walk around with still needs a little more attention regardless.
It actually reminds me of the Borg…
Thanks a lot! Your replies helped me. I’ve reconsidered my idea and decided to change the setting and style. It was good modelling practice so far, but a new scene will convey the message much better, I agree. I’ll start with redesigning my character and then trying to incorporate a human character to create more “action”. And then I will try to make the setting interfere less with the focus points. I’ve drawn out a new sketch and I’ll post some renders, as soon as I’m done with the setup.
Thanks again, I appreciate it very much.
I’ve came up with a new concept:
The idea was to make the scene simpler and focus more on the main action. I don’t want this appear too a political message, that’s why I didn’t design it as if Apple was taking over our world. The iPhone is more or less supposed to stand in for all handheld computers and show that some people might be controlled by their technical devices instead of the other way round.
I switched to Internal renderer, but now it’s quite hard to get rid of the totally black shadows and keeping up the dark mood. I’m using spot lamps with halo cones and ray shadows, as well as some spot lamps just for brightening up the shadows, without casting any.
Yeah the message is much clearer, me likes
Much cleaner scene. The message is a lot clearer. Although, I think you still have an issue with focusing on the main objects appropriately. I would play around with different camera angles and see if you might be able to fix the distracting off-centered feel to it. But great improvement! It’s a lot better in my opinion.