Here's a couple of quick hits on how I view my charter as an angel investor. Originally posted as a comment on Infectious Greed.
1) My #1 job as an angel investor is to help the company raise money. That means introductions and coaching, but it also means not doing anything to screw up the financing once the VCs are interested.
2) If I wanted to run the company, I'd start it myself. My goal is to avoid getting involved in operations. I'm there to provide advice and contacts.
3) If a company can raise VC money without any help from me, I'd certainly love to invest, but I can't see why they'd want me in the deal. It's my job to find those diamonds in the rough that can, with some intelligent polishing, become VC funded deals.
4) Conversely, that means that I have to be extremely careful in bringing deals to VCs. Reputational capital is hard to come by, and it's all too easy to blow it with a couple of dumb deals.