His rule #1 is “Keep them in the loop”. Years ago my friend and former colleague Kevin Donahue had many, many angel investors and found he was answering the same types of questions constantly.
So being a developer, he quickly put together a password protected web site and posted all his companies’ vital information regularly, mainly sales and financial data, but also milestones achieved and other information of interest to his investors. This saved Kevin a lot of time fielding phone calls and the investors were happy as well; they could take their time looking at the latest sales report or whatever interested them and only have to call or email Kevin if they had a question.
I’d advise any startup with multiple angels to emulate Kevin’s model, which with today’s tools is even easier, to not only keep your angel investors “in the loop” but your employees as well.