Take 1/2 payment upfront
When carrying out any work for someone. Insist on 1/2 payment upfront and make sure this payment covers all your costs and labour. The other 1/2 is a bonus to receive and can be used for good in the world.
If you fail to receive the full balance it is good to forgive that debt and trade again with that person.
But you yourself always try to pay all your debts in full as how we conduct our financial affairs leads a positive example of Gods people.