Do you freelance your app development skills? If so chances are you've encountered many frustrating arrangements where you end up feeling more like a slab of meat being punched at rather than a talented programmer with a unique set of skills you are using to make a product for a customer.
'Freelancing is running a business. Being the best coder or designer around won’t necessarily make you a good freelancer. To be successful you need to generate client leads, market yourself, build strong relationships, understand business needs, demonstrate your value, give accurate project estimates, and deliver on what you promised.' -Sherman Lee
Some clients can really take advantage of these types of things, and to better arm yourself to be the best business partner you can be and not just another 'piece of meat commodity freelancer' you can read this article by Sherman Lee.