You should not be 'angel investing'. Here is why: you don't have pre-established terms and contracts that state the exact terms.
If you gave me money with the only requirement being that I 'pay you back', all that means to me is. Give me $XX... I'll give you EXACTLY that amount back later on. No more, no less.
If you gave me money with the only requirement being that I 'pay you back', all that means to me is. Give me $XX... I'll give you EXACTLY that amount back later on. No more, no less.