One of the assignments for the photography class I recently took was to use your on camera flash.  I have to admit, I would never use my on camera flash for serious photography.  I’d only use it in an emergency if I had to get a shot and the lighting wasn’t sufficient.  These images dramatically demonstrate the difference that a single speedlight mounted off-camera can make.  I’m using my Olympus FL-50R flash, which I can control remotely from my camera.  I’ve used a small Lumiquest Softbox III as a light modifier.

Here’s a shot using the on camera flash.  Note the harsh shadows in the background, even though I’ve separated the flowers a fair distance from the background.

If you have to use your on camera flash, try to modify it in some way to soften the light.  There are little screens you can buy that will soften the light.  Here’s a shot with my modifier – a little bit of bubble wrap and a rubber band to hold it in place.  The light is a little softer, but still rather harsh.

Here are some shots with an external flash mounted on a stand.

Here’s what the lighting setup looks like.