Optimal Structure for Angel Investment

"What's the best/preferred structure of investment money pre-VC investment?... Assuming that you are planning on raising VC money some time in the future, there are two different typical structures for the first angel financing: (1) convertible debt and (2) preferred equity.

Convertible Debt: This is the easier approach of the two. In this case, the investment is in the form of a promissory note that converts into equity on the terms of a “qualified financing” (where qualified financing typically is defined by having a minimum amount – say $1m of total investment.)...

Preferred Equity: This is also known as a “light Series A” – it’s preferred stock that is similar to that a VC will get, but usually with lighter terms due to the relatively low valuation associated with it..."

Read more in this post from Brad Feld.