If I could give the world two pieces of financial advice that you should never deviate from and always follow, it would be the following:
1) ALWAYS GET A RECEIPT: One of my students in class today was upset because she said she paid her tuition with cash and they are saying she didn't pay. Whether she did or didn't, she said she didn't get or ask for a receipt. Ooooooh, people... unless you are paying with a check (and it wouldn't hurt even then), you should ALWAYS ask for a receipt, in fact, demand one. In this world, it's unfortunate, but you really can't trust anyone when it comes to money. And you also never know when the receipt will come in handy. People forget they got paid, people lie about getting paid. And if someone refuses to give a receipt, that's shady and they don't deserve your money. Even if you pay in money order and have the money order receipt, those can get rather tricky to track and you paid for them with cash, so it's best to get a receipt for those as well.
2) NEVER ACCEPT PERSONAL CHECKS: No way, no how! I don't care if it's your best friend, don't accept a personal check. Hard times happen. Good people don't intend for checks to bounce. Things just happen and whether it was an oversight, your friend didn't get their paycheck when they were supposed to, things happen. I don't know too many people that are so well off they can just leave checks lying around for weeks and not cash them. We all need to get paid, we all rely on getting paid, so when a check we accept doesn't clear, a snowball effect happens and pretty soon your house is being foreclosed upon and your car is being repo'd. Accepting business checks tends to be a little safer because most businesses are on good enough terms with their banks that if there is an overdraft, the bank will cover it. And unless you hear rumors your employer is going out of business, payroll checks are generally the safest.
Tip: An addendum to this would be that if you do find yourself receiving a check you're wary of, only accept a local one and take it immediately to the bank it was DRAWN ON and get cash for it. That way you are not liable for fees through your bank if it bounces, it is all put back on the account of the person who wrote the check.
Anyway, I don't often have words of wisdom, but these are a couple that I think everyone should learn!!!!