1) If at all possible, get to know the person you are doing business with, either via interactions on a page, public posts, in groups, etc. If they are local to you, insist on business being done in person where possible, in a reasonably public place with each of you bringing one other along to witness the transaction.
2) If the transaction is happening at your home, ensure someone else is with you as well. Some craftsmen, mechanics, bakers, seamstresses, work from home, so this won't be out of the question. Farmers often live on their properties, etc.
3) If the transaction involves a lengthy process such as building furniture, fixing a car, making a piece of clothing, etc, ask for half the price to be paid up front. This way, if a person decides not to pay you, you are only out half the amount and not the entire price.
4) While I am hesitant to suggest Paypal anymore due to their cancellation policy toward those who they don't agree with, online transactions are possible through such companies as Square. There is no registration fee for Square, and per-transaction fees are the same as those for credit card companies. You can set up Square to deposit directly to your bank account.
4.5) AmericaFirstPatriot has a way you can send money to other members inside your Advertising area. Get to it by going up to your round avatar in the top title bar, then click on Advertising. Click on Balance and Credits. You will notice a red "fund account" button. Click this, then click credit card (I'm told the affiliate earnings/points wallet may become a choice in this box too), fill in the necessary info and the amount you want to put into your AFP wallet. Beside the "fund account" button, is a "send money" button. When you click this, you can enter a member's name in the search box at the bottom of the window, choose how much to send them above, and finish the transaction. The advantage here, is that if enough users do business with each other on this site, the funds begin to circulate entirely "in house" and creates a bit of a micro-economy away from "the system". In addition, if a user stiffs another, they can be reported, blocked, or banned as admins think best.
The key to doing business safely in person is having others present to witness the transaction and not allow for any foul play to happen one on one.
The key to doing business safely online, is having recourse if the other person behaves badly toward the seller in any fashion.
An online community does best when everyone respects each other's time, effort, skill, and desire to be of service.
The world is changing. Let us create a safe space to help each other in trying times.