This will be the very first kind of money that we getting from investors besides what the founders put in. What are the legal rules as far as accredited and unaccredited investors, minimum and maximum investment? Any advice about pitfalls and steps to take so that if everything goes wrong, the relationships will survive?
You may find this article helpful: http://www.smarthustle.com/article/how-5-smart-hustlers-found-money-for-their-startups/
In short, one entrepreneur, who was looking to borrow money, founded TrustLeaf as he was encountering exactly this question and found no good solution. His new company now helps others gracefully, legally and safely borrow money from friends and family.