Mainly for beginners, but contains tips and tricks that can also benefit more advanced artists.
Contains detailed information on:
Choosing a reference photo
Creating an initial sketch
The grid method
Protecting and presenting your art
UPDATE: In the tutorial I recommended getting a good brand of pencils and I specifically named Derwent pencils. I no longer recommend Derwent. I now use Staedtler Mars Lumograph pencils. I also said using a scanner is ideal. I take that back. Scanners (at least mine) make the drawing look harsh and grainy. The part about taking a photo in bright sunshine, I meant to say take the photo on a sunny day, but don't let the sun hit the drawing directly. You can also take the picture indoors if you have a very bright room. Also, I no longer use a grid, but I still think it's a good way to get the proportions right.