While venture capitalist John Doerr can't pinpoint exactly what he will invest in, he's able to get pretty specific about what he doesn't care for.

"We're not interested in the next relatively inconsequential anonymous social dating site that will allow you to get laid before you get to the end of [Stanford's campus]," Doerr jokes. "We've ruled those out."

Doerr, a partner at Kleiner Perkins Caufield & Byers (KPCB), explains that even when a category interests the firm, self-imposed limits sometimes prevent it from investing. "We can't do everything," he says. That's why KPCB usually focuses on three broad fields -- biotech, new energy technology and information technology.

"Whatever rules I tell you, I want to tell you are just guidelines. The key to my business is every year we receive 3,000 proposals from entrepreneurs. We read them all. We take probably 500 meetings with entrepreneurs out of those 3,000," Doerr said.

He notes that the first thing the partners look at are the founders' resumes, which indicates that the firm leans toward betting on the jockey, not the horse. 

"Those will result in 100 second meetings," he continues. "And at the end we'll make 30 new investments per year."

For more from Doerr on what it takes to become one of the fortunate 30, check out the video below.