Your decision to sell your artwork or become self employed, will always lead to receiving clients. Clients will come in all types of requests and demands, but it will be your job to be well prepared for the project beforehand and throughout. The initial meeting process is crucial to know who they are and what they want from you, and most importantly, how you deliver the project to them.
There are times that you will work with clients who do not know what they want, and have come to you for some guidance and assistance. This process may take quite some time to nail down, as imagining something isn’t always as it is seen on a screen or print. Others can be very clear and ready, but not actually be able to get that image out on paper. So in both situations, you need to just guide your client to providing what they need as best as possible.
You will always have the option to point out to a client that your partnership/role on their project is not working out, for whatever reason, but do this in the most respectable manner. Not all people can work with each other, and it is just not a good fit sometimes. But take the time to try to rectify the situation, before that last resort.
Both the client and designer can create the best project, if there is an amazing partnership that includes great communication and understanding on all fronts. This is besides actually completing the project at hand, as this is a given (the target would not be reached if the designer was not capable). So always try to get an idea of the type of client you will be working with before signing any kinds of contracts.