I've gotten all my jobs by word of mouth. The first person that didn't pay me, I found out that he has a long list of people that he hasn't paid so I let it go

I've gotten all my jobs by word of mouth. The first person that didn't pay me, I found out that he has a long list of people that he hasn't paid so I let it go after several months. Since then, I've always limited how much I would do for someone until there was a long term business relationship.