Yes lighting matters the best lighting is natural light. At all coast avoid fluorescent lights it washes out the skin and creates a harsh look. Lighting should be thrown evenly on the face which will avoid shadows and hard lines. Imagine your doing a makeup application and half of the face is shadows what do you think your going to get, not a pretty site.
Also think about the look is it a day look or a night look you want to maybe consider a light design which can adjust. Lighting should also be along the side of the mirror or at face level..
If your really want to get professional you may want to buy a halogen lamp like Tungsten halogen lamp. They are costly but this is your career in makeup. But if your lucky you will be in the studio were they have strip lighting.
SO YES LIGHTING IS IMPORTANT!
I have had some awful picture's because of neglect of lights.