Stanford Business School recently conducted a survey asking hundreds of venture capitalists this very question. 

You can find a short summary of their findings in the linked article below. 

I won't spoil it for you by revealing the core few ingredients that these hundreds of VC's seem to agree on. But their approach is certainly encouraging for all of us starting and running small businesses. 

And if you're thinking about getting your business 'investor-ready', this is a great starting point, complete with advice from several Dragons and lots of resources and investor sources to explore: http://www.greatbusiness.gov.uk/are-you-investor-ready/