Most Helpful Girl
I am very, very pale, and I had trouble finding foundation that looked natural on me for the longest time until I found Loreal's True Match line. My skin is very oily in the summer and too dry in the winter, but just a little bit of this lasts me all day. I buy mine at Walmart, and I'm fairly sure that every display has a clear plastic tag somewhere that allows you to find your shade by holding your hand beneath sample spots (it was really helpful to me).
There are a variety of shades for skin tones that have warm, neutral, and cool undertones, as well as matching concealers and more than one form of foundation (loose powder and pressed in addition to liquid - I like to use just a little of the pressed powder on top for a smoother finish to my makeup).
Loreal also has a Magic Perfecting Base. It can clog your pores, but it is excellent when you have a stubborn breakout that doesn't want to cooperate with concealer - just make sure you wash your face very well if you use it.