Here's the model with that bounce card to the side. (Fig.26)
Little change, but to really see a bounce card, a little specularity and reflectivity on the model helps. So I'm going to change my Lambert to a Blinn and adjust the Specularity, Eccentricty and Reflectivity settings a bit: (Fig.27 & 28)
So here, you can see how you can slightly see the bounce card being reflected in the side of the object. It adds some interesting detail having these around, especially in a scene with nothing to reflect. They use these a lot in car ads to add those interesting highlights in the paint. They are great for getting highlights in eyes as well. If you didn't want it to be reflected you could turn the reflectivity off in the shader, or check it off in the render stats of that polygon plane. As well, you could make a bigger plane, or half cylinder and texture on an image of the room in the color channel and ambient color channel, and get the colors from the image to bounce over the object.
After about this point is when I would start designing my shader and tweaking the specular settings and such. Much the same way we did the lights, focusing on one attribute at a time, and often turning off the other attributes so I can see what it's doing as I'm changing it. As you get better you get a feel for what does what, and don't have to turn stuff off so much, or can tweak multiple lights at once because you have a good idea of what's going on and what should happen. As well, I consider shader design part of lighting. So I wouldn't got any further with the lighting without making my shaders to see how they handle the lighting and are doing what I need them to do. This is about as far as lighting goes without well designed shaders, and you can't tell if a shader is working properly without good lighting.
So there you have it. Hope you learned something. Not the best end example ( I would have taken it a little farther, but I was so busy making images in Photoshop for the tutorial, I forgot to save the scene and it crashed when I tried changing something), but really, the process is no different. It's just more time tweaking everything, which is the long part. I would call this image far from finished, but from here it's just observation of references, trying to figure out the properties this image needs and tweaking all the same light settings we already have and adjusting my shaders.
One challenge you are always facing that I haven't mentioned is composition. One tip on composition is the eye is drawn to the biggest brightest fasting thing on the screen generally. The windows in this image are bright white and the model is darker than them, and the room around the windows is dark, so the eye is first drawn to the windows instead of the model, which you're trying to make the focus of your piece.
Now if the whole image was lighter and the head was darker, and the model had the contrast against the background image, then even though the framing image is brighter, the eye could be drawn to this darker floating center, as if we reversed the concept. Color could also really help here. A yellow orange, warm tone bronze metal head against this cool colored background could bring it out as well. Faking the lighting by having less lighting on the pedestal and more on the head, so the other parts of the model aren't as bright as the face, could also help direct the eye where we want it. Luckily it's a face, which is one exception to that "rule" (though I don't like that word, It's more of a general guide. There's no rules. Just what works.) and the human eye is drawn to human faces, so you have that working for it. (Really, I could right a whole other tutorial on composition, but it's worth mentioning here because part of the goal of good lighting is to control the composition. Despite what most 3D layout people would tell you, I believe you haven't done your layout until you light it. If that background image was just a grey 3D model that wasn't lit, imagine how flat and lacking in contrast it would be. Once lighting is added, it has a completely different composition.)
As far as what I consider good composition, your eye stars at the biggest brightest thing, and then moves to the next biggest brightest thing, and so on and so on. Good layout will have something that helps direct the eye to the next thing, and in good composition nothing leads the eye outside of the frame of the image and tends to bounce it round between a number of features. Look through some of the better paintings you've seen and you'll see the pattern all over the place. Observe some of the works you don't like and try to figure out what fails about the composition. It probably doesn't pull your eye in the right places, or leads your eye no where, or has only one thing your eye is drawn to. The more of this you figure out, good and bad, the better work you make.
And then on top of that with composition and lighting, we talked about key, fill and back light and biggest brightest thing drawing your eye. These are guides. Not rules. Think of the concept of what these are trying to do, not that you always need a back light. The purpose of adding a back light is to break up your image from the background. Now if you have a character on all white background would you light them with a really bright white back light? No, because where they were once defined from the background you've now added this light that blends them into the background, which defeats the purpose of a back light.
Your key light could be a really dark light if that's the mood of the image. The goal of the key light it to define the features of what it's lighting. A dim light in a dark scene can do that. The fill light is there to soften up overly hard shadows and help diffuse the light more. Any of these could be one light and any of them could be 20 lights. As long as they're completing the concept of the reason you add them into the scene in the first place.
So on any of these steps, if you can't come up with a why for why you are adding something, don't add it. If you don't have a reason you decided to pick a color, figure out why. All the colors I added to the lights balance it out more with the colors in the image. I added colors that were already found in that image. I didn't add any purple or red (though I could of for contrast, if it was the right contrasting color). I did add a slight bit of yellow/orange, but that's on the concept that sun light is either soft blue or soft yellow/orange and that's your light source from the windows. The bounce light is off a green floor and thus more green. But I have a reason, a logic, to all of it. There's never a light over the top of the model, because the image shows no light source from there. I tried to place lights where other light sources seemed to be coming from. So figure out why you add anything to the scene, or you don't actually have any control over it. Without understanding or reasoning, you're out of control and it's just luck if it works out and you probably can't easily repeat it.
Anyway, I know that was a lot, but I hope it helped. I know I always wished there was more info on this stuff when I was learning, and these are the big concepts for me. There's plenty more tools out there, but I've found I can get pretty far with these concepts in mind and don't need that many tools to get a nice look.