Who has bought your product before? This is your number one statistic to determine who to sell to. This can also be a huge help in identifying who you need to target your message to by defining your audience.
I like to use the example of Britney Spears when she first launched her hit “Baby One More Time” (before she turned temptress). She was coming out of Disney years and becoming an individual female sensation. It is very clear that she was not directing her music for men to buy: in reality, she was appealing to a female audience.