I was once counseled by a wise old man that, you lend only what
you can afford to lose.
therefore in deciding whether to lend or not, you always do so on
the basis that you will never see a single cent back. See it as no
different from giving, therefore your decision tree should be
:
1) can I afford to lose $XXX; if so,
2) is the "borrower" worthy of a $XXX gift from me.
That way you mentally prepare yourself to lose everthing and you
never lend more than you can afford to lose. The same principles
are applied in banking.
So remember, never lend only give. Happy giving.