The document discusses how to be a successful angel investor. It begins by introducing the author as a serial entrepreneur who has invested in companies like AirBnB, Square, and Stripe. It then outlines ways for angels to lose money, such as being momentum-driven, short-sighted, or unhelpful to founders. The document recommends angels seek gaps in capital, expertise, or industry focus. It also notes trends making valuations high, a Series A crunch, and increasing transparency in deals. The author concludes by saying whenever attractive people enter an industry, it may be overheating.