It is great whenever you can properly set up lights and systematically work your way to the final image, but that simply is not always an option, especially if you are doing something like shooting weddings. However, that does not mean you simply can't use artificial light; you just might have to be a bit more nimble with it. One of the most popular techniques for this is bounce flash, and this great video tutorial will show you how to use it properly.
Coming to you from Andrew Boey with Beyond Photography, this awesome video tutorial will show you the ins and outs of shooting with bounce flash. If you have not seen it in use before, bounce flash is a really useful technique in any scenario where you want to create flattering light but do not have the time or space to set up more traditional lights and are forced to use a small speedlight. The problem with a speedlight is both that it is on axis, which rarely results in desirable results, and that it is small, which means it produces hard light. The idea with bounce flash is that by aiming the flash toward something like a ceiling, you essentially turn the entire surface into a large light source, making for more flattering results. Check out the video above for the full rundown from Boey.
TTL does NOT mean automatic. TTL means: "Trough The Lens". The amount of light from the scene is determined by measuring the reflected light from the surface of the film (analog) or the sensor (digital).
And No, you don't use your shutter speed to control flash light but to control ambient light. You use the aperture to control the amount of flash light.
An No, not the bigger the light is, the more ambient the light is. It depends on the size of the diffuser and(!) the distance from the subject.
And No! This video is not awesome. It is cheaply made and 3 of 9 minutes is self-promotion.
Alex, either you have a really bad taste or you don't care at all. I'd say, both!
Hmm. Not very useful if you have green walls!
I liked this video and thought it provided useful information in a concise manner. Contrary to what a previous comment stated, I believe it is fair and accurate to characterize TTL mode as automatic. It automatically adjusts the intensity of the flash based on shutter speed, ISO, and ambient light. Again, contrary to a previous commenter, I don't think the self promotion was overdone.