First impression is usually made during first 2-4 minutes. And it is usually the most objective a person may ever get. Here are different looks you may use in different situations:

Image: maturity, prudence and life experience.
Neat, clear eye-brows, bright lipstick and arranged hair speak about your confidence.

Mysterious and skittish

Image: thoughtless flirt or intriguing mystery
This image is very attractive for many guys, though may scare them away in some cases
How to get it: use dark eye-liner and sparkling champagne eye-shadows. Apply them to the eye-corners or bottom eye-lid to enlarge your eyes. Shade your cheeks with pink rouge or skin sparkler. Use pink lip gloss. Curl up your hair to make careless locks.
When appropriate: when you want to be a number one at a party or seduce a cute colleague.

Feminine and elegant
Image: elegance and light detachment. To look like that you have to be moderate at make-up and style.
How to get it: City girls are usually pale