Trusting the Process
I can't believe I'm saying this, but I've been an interior designer for 21 years! And for 16 of those years I've worked for myself and for that I am so thankful. It's taken me about 15 years to finally put together a {process} that works for my business, my clients and me. I've read a lot of books, attended countless seminars and have made a lot of mistakes to get to this point, but it was all part of the journey. My biggest piece of advice, when working with any interior designer, is to trust their process. A good designer will be up front about how they work and will explain it during your initial meeting, as well as in their design agreement. This should include how the selection process works, what to expect during presentations and how much their services will cost. Following the process will result in exactly what you hired your designer to do - create a beautiful space that reflects you!
Good design is truly multi-faceted. Of course there is the room design, but there's also all the behind-the-scenes work a client doesn't see. Putting together a workable budget, placing all the orders, working with the seamstress to make sure your window treatments are the perfect size, keeping the warehouse updated on what's arriving, making sure the table that arrived broken is replaced, scheduling the painter, picking the perfect wood stain color for the sofa legs and keeping those hundreds of notes they have taken organized. All of these "details" are an important part of the process.
My other recommendation is that you let the designer do what you paid them to do. Trust that they understand your vision and will bring it to life. Trust that they will only suggest good quality products that fit in your budget. Trust they will deliver a room you will be be proud of.