Since our first DSLR photography lesson Mohammad bought an external flash (Canon 430EX II speedlite) to pair with his Canon T2i, which is something I highly recommend to all my students as the best next piece of photography gear to buy, after the initial DSLR and lens purchase. The popup flash on DSLR bodies (or any camera) produces very poor results and has a very limited reach. If you like to photograph people, then an external flash (strobe) is basically a must.
We once again met in downtown St. Petersburg finding various overhangs and walls to practice bouncing the strobe off of. Even with an external flash, you do not want to just blast the light directly onto the subject, which will produce blown out skin tones and harsh shadows. So what you can do is have the light from the strobe bounce off something so that it hits your subject indirectly. This indirect light is scattered and soft. That kind of light is good for producing professional looking portraits.
While I was being the model for Mohammad's practice shots, he remembered to use the rule of thirds while photographing me. So since the lens was not pointed directly at me, the head of the flash would need to be redirected more toward me (the subject) or a bouncable wall. External strobes like the 430EX II have a multidirectional head. So the lens can be pointed one way, and the strobe another. This is another advantage an external strobe has over the built in pop-up flash.
New in the lesson was also shooting mostly in manual mode. Mohammad quickly realized that being able to get away with f/8 and f/11 for almost all shots taken in direct sunlight is not the case when using external flash as we often had to very finely tune our apertures and shutter speeds to produce the best exposures. As you can see, I used f/6.3 for the above shot.
Now, as better an external flash mounted on a hotshoe is over the built in pop-up flash, getting that external flash off the camera is that much better than having it on the hotshoe. I look forward to a future lesson with Mohammad where we practice off camera flash. I recommend reading the STROBIST blog if you want to get a daily dose of lighting information.