Paul BuchheitPaul Buchheit, the Gmail creator who recently joined startup incubator Y Combinator, just published a blog post summarizing his first three years of angel investing. It’s important reading for any wannabe angels, because the post gets specific about his returns, rather than just offering generalities.

You may remember that we wrote about Buchheit’s winning streak a year ago, shortly after his investments reMail, AppJet, and Mint were acquired. So how much has he actually made as an angel? Buchheit said that around half of his 32 investments have either died or been acquired so far, making him a total of $1.34 million. That’s only a 10 percent return on the $1.21 million he invested, but he said, “At least I’m not losing too much.”

Plus, there’s the other half of his portfolio that’s still alive and independent and could therefore bring him a lot more money.

As for the existing exits, Buchheit divides them into categories based on how big his return was. Cloud hosting provider Heroku and personal finance service Mint returned more than 10 times his investment. AppJet and 280 North were “medium-sized” returns, while Auctomatic, Parakey, and Zenter were smaller exits, returning 2-3x.

Buchheit concludes with two pieces of advice: “1) Assume you’ll lose your money and 2) Plan on investing in a large number of companies.”