Vipin Jain, founder and CEO of the electronics shopping site Retrevo, says it's easy for entrepreneurs to get distracted given all the innovation that needs to get done at a startup.

The biggest challenge, then, is "how do you focus on the core product, the core concept that you want to build, and rally the team around that?" Jain says.

Second, it's easy for startup execs to fall in love with their idea or business plan, which can blind them to things going on in the market.

"Be absolutely paranoid about your idea," says Jain, who explains the value add of Retrevo in this pitch and the company's rating system in this interview with Vator.tv's Bambi Francisco last week.

Jain, who completed an $8 million funding round last week, advises CEOs to start raising money way before they think they will need it, because "it always takes longer than you think." 

He also advises not spending money on marketing until you know which products will be profitable and what the return on your marketing investment will be.