Five pigments I recommend to a beginner are:
Your Ladyship: recently discontinued, you should still be able to find a jar. The shade isn't a bright white, so it's great as a high light (brow, cheek, etcetera), mixed with lip gloss, used to tone down bright make up, mixed with foundation for shimmer, or as a sheer wash of color across the eye lid
Pink Opal: similar to Your Ladyship in that it has a huge amount of uses. While Your Ladyship has a very slight orange tint to it, Pink Opal is like an opal in that it reflects pink. It can be used for all the same uses as Your Ladyship, and I love using it as a high light on my cheeks, and mixed with lip gloss (the pink reflects are gorgeous!)
I think purchasing Pigments that have multiple uses is very important, especially when starting out! My advice is to get samples of colors you like from MAC, and purchase full size containers of the Pigments you use most often. Ask about pigments that will make your eye color pop, too!
I don't recommend Chocolate Brown Pigment or Teal pigment, because MAC has labeled them as unsafe for the eye area. I do own Chocolate Brown Pigment, though I'm grateful to have found out it shouldn't be used near the eye area before using it! I use it for bronzer occasionally.