David S. Rose (founder of New York Angels) has founded six startups, and funded 80 others says he looks for:
  1. Large and growing market
  2. Real domain expertise
  3. Provable product need
  4. Scalable business model
  5. Competitive advantage
  6. Platform/partnership/bizdev/API strategy
  7. External validation (ideally traction and/or passionate customers)
  8. Viable business structure and cap table
  9. Reasonable valuation
  10. Proven team (tech/product/design/marketing/sales/domain/etc.)

But most important of all, it must have an entrepreneur on whom I’m willing to bet on. And the attributes I look for in that entrepreneur are:

  • Integrity
  • Passion
  • Startup experience
  • Personal domain expertise
  • Operating skills
  • Leadership ability
  • Commitment to the venture
  • Long-term, extensive vision
  • Realism and pragmatism
  • Flexibility
  • Even temperament
  • Coachability
  • Alignment on vision

Source: Quora
Image taken from: NYTimes