Where do you put light switches to control the light to your basement?

In any situation you want the switch located so you can have light before entering the space. With basements you might use what is called a 3-way switch with one at top and one at bottom of stairs. Think about how you are going to use the space. You wouldn't want to put a single switch at the top of the stairs and then have a TV room downstairs and have to go up the stairs to turn off the lights and then go back downstairs to watch TV. The more control you have over the lighting you use, the better you can tailor lighting to the activity being performed.