how can i secure my private lender?

[Ely Santiago]

 I have a potential private money lender for rehabing that i am talking to but he wants to make sure he will get his money back and how it will be secured. I've tried doing research on mortgage liens and insurances but i cant really find specific ways i can secure his investment and persuade him to invest. Can I direct him to a 1st position lien or do i just need a good rehab spreadsheet to show him? How do more of the experienced guys build their lenders trust? I am also just about to turn 18 and I think real estate is the way to go for me.