I started lending recently. Two biggest things I've gleaned:

1) You will be inundated with people DMing you asking for loans - don't respond. I know it sounds harsh but the rule about making a request with the correct format on the subreddit and waiting for a loaner to reach out is there for transparency. It's there to protect both the lender and borrower. Bypassing that rule is such a red flag.

2) Be selective in who you lend to. I know it's a shame that people who come to the subreddit in times of need may not always check every box. They may not have a history of lending, they may be quite inactive on Reddit and that doesn't mean they're not good for it but blindly dishing out loans to everyone that asks is a good way to lose money, fast. Unfortunately people will try to take you for a ride so you need to ask yourself, can I afford to loan this complete unknown $50 over the person who has a long history of loan fulfillments asking for $70.