If you are going to lend without collateral, you need to be sure that you know him in RL, you want to make sure that he lives in a court jurisdiction that is close to where you live and that is willing to enforce contracts, and to properly document the loan agreement in writing.
If you are friends with the person borrowing money from you then getting repaid hopefully should not be a problem (especially if you are lending only small amounts) as I would at least hope that he would not scam a friend. However you do want to be sure that you have a way to enforce the loan agreement in the event that he defaults
EDIT: I just realized that you you said you will not lend without collateral. This makes it a lot simpler. You need to have the borrower send something that has a stable value and is liquid to a trusted third party escrow, then you send the bitcoin to the borrower once the escrow confirms receipt of the irreversible collateral. Once you have been repaid with interest the escrow will send the collateral back to the borrower
If you are lending out here, you need to get an escrow to hold the collateral as they can not be sure that you are not collateral scamming.
