First thing is practicality! Make sure that there is plenty of light, if possible, some natural light but certainly lots of shadowless artificial light. You can achieve this by creating a light "triangle", light coming from above (recessed or ceiling light) and light from the side (sconces). That way you will ensure that there is even light over the face.
Have lots of counter space. I think about 48" is a minimum, otherwise it will start feeling crowded and unpleasant.
If at all possible a tiny sink is a great addition, just a place where you can rinse your fingers or dampen a sponge.
Find a good, solid upright chair. A dining chair is perfect. Don't succumb to the girly upholstered thing, that will leave you sitting too low and far away from the mirror.
Finally, lots and lots of storage. Try to keep as little as possible on the counter top, it will make it look fresher, and a more pleasant place to be. Also, lots of storage will help you keep everything well organised.
In today's busy world it seems like a little bit of an outdated concept, but I am seeing a rise in popularity of the vanity table. I did the one above a few years ago, but it remains one of my favorites, it has a certain glamour that I find really appealing. Here are some thoughts to consider if you are planning one:
