[CaptainJustin]

The following is my opinion. Others may have a different take on these ideas.

- Not charging enough from the start. Two clients accepted my rate way too fast.

- Giving time estimates for every piece of work rather than price estimates. Price estimates allow to you to charge for the value you provide rather than being limited to the negotiated hourly rate. Some tasks take a great deal of expertise and provide massive value but take only a short time. Don't bill them by the minute for that. Bill by value.

- Limit the number of changes they can make after completing a task or charge per hour after initial delivery. Some clients will take every opportunity to tweak something. It never ends. If that is happening on your (unbilled) time then your effective rate is falling with every new "quick change".

- Don't hand over work until the payment experience for a new client looks to be in good faith, regular and business usual. I've heard a few stories from friends about serial-exploiters who churn through freelancers trying to get most of the work done for free.