One thing that is common for Angel investors and VC’s to say is that they really like your business, but it is too early stage and to keep them in the loop as you make progress. This is likely because it is too early stage to meet their investment criteria and also because they want to see what you can accomplish over time. My favorite article on this topic is Mark Suster’s Invest in Lines, Not Dots where he talks about seeing what a founder does over time and building that relationship
So the next logical question a founder should ask is..how do I keep investors up to date with my progress if I am busy running my company? I would recommend a monthly email newsletter that you send to both your current investors and potential future investors. It should include all of your key performance indicators and financials as well as a qualitative report of what is going on. You should also be sure to mention specific things that the readers could help with including hiring, connections, advice, etc. Most investors are more than willing to help out of they can. Jason Calacanis’ article on “what should I include in my monthly investment update” goes into more detail.
Asking an investor if they would like to be on your investor newsletter and see the behind the scenes of what is going on will be very well received. As far as making it happen, I would recommend either a mailchimp or emma email newsletter or using a tool like https://visible.vc/ so that your email can be as visual as possible.