Ask HN: How to handle angel investor interest?

Our product has entered the launch stage and we are doing a kickstarter. I had asked a bunch of people for feedback before going live. One of them has expressed interest in being an angel investor. I had never given any thought to this. How do I handle this? Do they take a percent of company for the money. Is there a contract similar to YC? Is there anything I should look out for? Here's the link that created this (not meant to be a plug) https://www.kickstarter.com/projects/100-xyz/298281515?ref=578000&token=e80d409c Thanks