I have this client that is SUCH a micro-manager. I keep trying to help them understand that they hired me because I am very good at what I do but still, they micro-manage. What can I say to them to help them trust me?
Ah yes, the age-old micro-managey client. While I don't really know the specifics of your situation or history with this client the one thing I can usually point to on this, is communication.
9.9 times out of 10, if a client seems micro-managey, the problem is with us, not the client. A client will fill gaps, so to speak, if we do not provide them with the information they need that allows them to trust us. Our process has to be clearly defined in order for them to trust us. And not just in a big general schedule outline - actually talk to them.
As a designer/UX-er/developer (whatever it is you do) it is entirely your job to communicate your plan, set expectations and deliver upon those fully. Often, we think we are doing all this but if you really look closely you may see some places in your process of communication that you can tighten up. It will often feel like you're over-communicating but our processes are often super confusing to clients. If they could do what we do, they wouldn't hire us. But we need to make the experience of working with us as friendly and easy as the experience we're trying to create for them.
Here's an example from an actual project I coached on a while back, where the designer was going to be working directly with the client on a two week illustration engagement.
10am Monday: Project kickoff, client is told by designer that he will follow up asap with a schedule for the week. (Plans to send first thing in the morning.)
8am Tuesday: Designer receives schedule from client. Designer is frustrated because it is not the right sequence or way he would like to work.
The designer genuinely thought he was communicating awesomely by letting them know he would be providing the schedule and sequence of events. He expected they would be fine until they received it. He was shocked the client responded with their own schedule, especially since he'd been already been working on the schedule he promised. This suddenly felt imposing, like the client didn't trust him, all the good stuff we complain about with clients and the project was just starting.
Where he fell short on his communication was using a vague term like "ASAP" which to him may mean 'first thing tomorrow morning' but to the client could mean 'in an hour or two.' When they haven't heard anything by the end of the day, they sort of panic and thusly, resort to micro-managing the situation. If things aren't defined for them, they will take control of the situation.
We need to set ridiculously clear expectations with clients. Maybe something more like:
"Dear Client, I will have a project schedule in your inbox by 10am PST tomorrow morning."
At which point, you better deliver at or before 10am PST. If you do fall behind or need more time, communicate as swiftly and concisely as possible. A lot of us don't even realize we're using vague terms when we communicate but it happens so often. Being specific sets the expectation that if they check their inbox tomorrow at 10am PST, they will see the schedule as you promised. There is no sense of wondering when they can expect it.
This is a small example but it's the smallest detail in the words you use when communicating with your clients. Set timing expectations down to the hour, minute and time zone. Whenever possible, set the expectations of what happens after the next step.
"Dear Client, I will have a project schedule in your inbox by 10am PST tomorrow. Once that is sent, I will begin Step 1 but please contact me if you have any comments or concerns about the schedule. Otherwise, let's plan on our next touch-point call on Wednesday at 2pm PST to review Step 1. Upon review of Step 1, in order to keep on schedule, I will need your feedback no later than 10am PST on Thursday."
You've clearly set the expectation. There is no question about what's next. Ease them through each step of the schedule by recapping what's been done, what is happening and what to expect next with as much specific detail as you can. Encourage them to communicate with you if there's anything they don't understand but most of the time you'll know you're communicating well when you feel like they trust you.
I could go on about this for a long time and it's important to note, if you didn't start the project off on the path of excellent communication, it's a hard thing to recover from mid-project. It's so, so important to start out on the right foot from the beginning. If that's not possible, you CAN still improve communication at any point in a project and you're likely to see really positive results. I do have an arsenal of examples for different client-communication situations, so if there's something more specific you're working through, by all means, ask more!
The summary is, if your client seems micro-managey, do some introspection and examining of your own communication style. I'll bet that improving your communication efforts, improves the trust, which eventually removes the need for your client to micro-manage.
With humble thanks!