The article Max mentioned, 4 ways to get rejected by an angel, had a follow up piece on Venturebeat, 4 MORE ways to get automatically rejected by an angel investor.

The follow up calls out:

• Having a big monthly burn
• Pretending this isn’t risky
• Not interviewing the Angel
• Not having an exit strategy

I particular like the part about pretending this isn’t risky. I can’t even begin to remember all the ideas I’ve heard that are sure things. Working with an investor should be a healthy relationship, not one started on a false premise.  Everyone knows startups are risky.  If they weren’t, everyone would be doing them, and be a huge success.  Be honest and give all the facts, but show why your calculated risk has a good chance of working out well for both of you.