Firstly, find something to use as a backdrop (I used a towel), and lots of lights. Set all of this up so that it's brightly illuminated. Put the figure in question slightly in front of the backdrop, making sure the light's on it.
Alternatively, take the photo outside on a bright day - either works.
Now, here's the four tricks I use.
1) Find the macro mode (not the Marco mode ;D), usually a button with a little flower. This will tell the camera it should be focusing at shorter distances.
2) Turn off the flash. You should have enough light you don't need it. (If you don't then turn it on, but it's preferred that you don't use it - because at these distances, it can cause overexposed areas on the photo.)
3) Turn ON the 10 second timer - this is so you can set up the camera so you're not touching it when it goes off, and it's a much steadier platform.
4) Set the camera for 4x zoom or similar (or as much as you can if it's less than that). This means the camera has to be further away from the model, which helps eliminate depth of field problems. (i.e. parts of the model being in focus when other parts aren't).
Set up the camera so it's facing the model and the shot shows everything you want it to. Also make sure it's actually willing to focus on the model. A half press on the button will usually tell the camera to find focus - make sure this is right if you've got live view. If not, move things around and try again. If it really doesn't want to work, try turning off macro mode again, or reducing the zoom used.
Press button, step back, and don't touch any of it until the picture is taken. Because it's all steady, focused and with a longer depth of field, you should get a better picture.
Also, don't feel you have to go with your first attempt. If it doesn't turn out great, move some things around and try again - it's digital, so you can take plenty of photos, then select the best when you've transferred them to your PC (or your Mac, if that's what you've got).
Once on your computer, you can then take the picture you've got, and if you've got a decent image editor, you should be able to use the "Levels" control (or equivalent), which allows you to view and adjust the histogram for best contrast and brightness. Crop the image as appropriate, then upload to whichever hosting site you use.
This technique works well for most model photography. Don't feel forced to use it, but if you find you have trouble with taking photos of models, you might like to try it.
