If you have little or no experience with makeup:  
1.  First and foremost, learn how to match foundation to your skin tone.
2.  Try to learn what brand of makeup works best with your skin (example, I love MAC lipstick and foundation, but their eye shadow won't adhere to my skin for some reason, so I use Urban Decay eye shadow).
3.  Learn how to contour.
Clothing:  learn your sizes, top and bottom.  Learn what works with your shoulders, waist and hips.  Try to work out some sense of your personal style.  (Example:  I prefer to wear blazers and skirts to work, and T shirts over skinny jeans or jean shorts at home).
Most important, have fun!