One of the key differences with collaborating with clients vs co-workers is the nature of your relationship is much more transactional. You have been hired usually for a short amount of time to do a specific thing because you are an expert in this. You may never meet the client face to face.
If you’re working with a co-worker day in and day out it’s much more likely you’ll listen to their ideas, take long discussion etc because you have to see and work with this person every day. You don’t want to upset them.
Now I’m not saying you should go around upsetting a client. I’m saying your relationship is more that of a doctor and a patient. You are the one with the knowledge and skills guiding them as to how to tackle their problem as quickly and efficiently as possible. (Because time is money.)
A solid brief is key to the collaboration process, but it’s also important to consider the core of what you were hired for. If you were hired to design a brochure then the core problem is that your client needs more customers. Know who those customers are, what appeals to them, what the competition are doing. Armed with this knowledge semantics like if something ‘should be yellow or blue’ are small fries. As long as you can ultimately justify your decisions to that core aim.
Any project is a series of decisions, all of these decisions need to be right for the brief, but it’s your job to guide the client through a process so that they aren’t concentrating on those small things straight away. There was an analogy I’m very fond of about a painter and a wall that goes like this:
The first stage of review I’m going to show you 3 prototype choices. These like test pots on the wall. Once you’ve decided which colour works best, I’ll go ahead and paint the wall but take your time because once it’s pink I can’t change it back to green.
Once a basic concept has been chosen, I will paint the wall. This will be a rough version of the final product. This is still not a finished product so take your time, sleep on it and think carefully about changes because once the final coat is on, I will have to charge you more to paint any further.
I found in most cases that this process was very effective in reducing the amount of changes needed but also in emphasizing that someone had a limited amount of my time they were paying for.