Deposit percentage for high risk client?

I have a potential client who I consider high-risk. He is a young business owner who is in the process of having some products manufactured in China, and needs to start marketing them. He has no established business, has never sold a unit, but has high hopes and a reasonable budget for marketing.

So, short story long, I’m interested in taking him on, he has a neat product that will be fun to market, but if his manufacturing falls through / his partner dies / his boat from china gets eaten by a giant fish - I don’t want to get screwed. High risk.

Anyhow. I’m just curious what percentage of the overall fee you typically charge.

[whisper]If you’ve never had a paying client in your life other than your grandmother / uncle / mother please refrain from making any useless comments.[/whisper]