Here's what you need, and my current bottle of choice:
Sheer pink-y white for a no-polish-but-better look: Essie Ballet Slippers.
Red - I like to have a deep blue-red and a bright really red: OPI Got the Blues for Red and Chick Flick Cherry, respectively.
Bright, hot pink - Revlon Cherries in the Snow, or OPI Cancun Fiesta (although I'm on the hunt for an awesome OPI hot pink from my last manicure, I thought the girl said Pink Flamingo, but think maybe she said Pink Flamenco?)
Dark and sexy, formerly gothic - I alternate between OPI Lincoln Park After Dark (of course.), Maybelline Denim Dash, and Revlon Black Star.
And lastly, the granite shade: OPI You Don't Know Jaques! (This is my least favorite of the color categories, and the one I wear least. I'm not even sure why I keep it around, but I always wind up going back to it.)
(And of course, a clear top and base coat. That's a must-have.)
I actually googled "nail polish wardrobe" and found this post that completely validates my own beliefs, but with a lot more insight added to the categories and generalized to work for everyone. I highly recommend!