Once you've gotten your flash separated from your camera, you have lots of options. The purpose of bouncing your flash when you leave the flash in the camera's hot shoe is to get the light to fall on your subject from an angle and not straight on. The latter creates flat light, whereas the former will produce shadows on your subject's face, thus making your subject appear more three dimensional, as in real life, instead of two dimensional on a flat image. By moving our flash off the camera, we can accomplish this same thing, creating flattering shadows to make our subject more real looking. So, where shall we place the flash to accomplish this look? If you think of the scene before you as the face of a clock where your subject is in the center and you and your camera are at the six o'clock position (0° on the circle surrounding your subject, if you will), the standard approach is to position your flash on a stand at 45° camera right (sort of between the 4 and the 5 on the clock face). And then extend the flash stand up so it is approximately 45° in the air pointing down at that angle toward your subject. Of course, this is just a starting point. After a test shot or three, you may want to move your light stand/flash one way or another, depending on the look you want. I have written about light positioning before, so take a look at this post on the "lighting compass," as Syl Arena calls it: http://www.infotor.com/blog/take-position-your-flash-on-the-lighting-compass/. You can find many articles on the web about the different styles of lighting, "Rembrandt lighting," "broad lighting," "short lighting," etc. check these terms out and experiment.
The other aspect of light positioning that getting your flash off the camera affords you is how far your flash is from your subject. Flash-to-subject distance naturally impacts the intensity of your flash's effect on your subject but and, perhaps, more importantly, it affects how much light falls on the space behind your subject, your background. Again, I have written previously about this at http://www.infotor.com/blog/flash-friday-using-light-fall-off-to-your-advantage-making-the-background-black/. The important thing to grab onto with regard to flash-to-subject distance is how the Inverse Square Law (ISL) affects how much light falls on your subject OR on the area behind your subject. The ISL sounds very confusing but is, in fact, quite simple and useful to photographers. (Check out my discussion of ISL at http://www.infotor.com/blog/flash-friday-strobe-position-is-one-thing-distance-is-another/) Basically, the thing to remember is that the closer your light is to your subject, the faster it drops off not oblivion. This is one way to make a background - even if it's a white wall - turn black or, at least, gray. However, if you move your flash back a few feet, then your background will get lighter, or rather, exposed at closer to the same level as your subject. You can use this knowledge to change how you produce your images.
I am offering two new classes this summer: "Mastering Manual" and "Mobile Flash: Using the Flash Stick." Check out the descriptions and register online at http://www.infotor.com/photoclasses/plannedclasses.php. I am also available to do one-on-one tutoring or small group lessons designed to meet YOUR needs and what you want to learn in the area of photography, using flashes, or the use of Apple products and software. Give yourself the gift of learning: http://www.infotor.com/photoclasses! Check out my new special tutoring bundle: http://www.infotor.com/photoclasses/tutoringbundle.php!