Show Me What You Mean
The fastest way past a vague brief is to put something on the screen and ask what people see.

I.
A client tells us they want their new website to be "engaging." Everybody in the room nods.
I hear engaging and picture motion, somebody exploring for ten minutes. The client hears engaging and pictures a buyer finally understanding what they do in thirty seconds and picking up the phone. We both sign off on the brief. Then the first design shows up and somebody finds out the agreement wasn't really an agreement.
That's the most expensive possible moment to learn what a word meant.
II. Give the disagreement a shape
Liz has a way of handling this that I really like. Before anybody designs anything, put a handful of really different websites in front of the client and just talk through them. What do you like? What makes you want to leave? Then build a homepage direction from that conversation before it spreads to the rest of the site.
The client doesn't need a design vocabulary for this to work. That's our job. They just have to be able to point.
"This opening feels slow." "This is how I wish our product got explained." Suddenly engaging means something specific. Even a reference they hate is useful, because it shows you a boundary nobody would have thought to say out loud.
III. The reference isn't the instruction
Say a client loves a site with a full-screen video at the top. The easy read is that they want a full-screen video.
Ask why they like it, though, and the answer might be "you can immediately see the product being used." That's a different assignment. Video might be the right answer. So might one great photo and a really clear sentence. Copy the visible feature before you understand the reason behind it and you've boxed in the work way too early.
The reference is raw material for figuring out the instruction.
IV. Taste still has to meet the job
This cuts both ways. If a client says "modern" and I quietly translate that into my favorite style, that's on me when they don't recognize their own request in the result. I filled in the definition without checking it.
But treating every preference as a requirement is the opposite mistake. A client can love a reference built for a completely different kind of business, solving a completely different problem. A company selling something unfamiliar might need to show it working. A professional service might need to make it really clear who's responsible for what. Neither one should borrow the other's structure just because it looks impressive.
That's honestly the part I find most interesting. Two people can love the same image and disagree about what job it's doing. They can hate a design and still learn something from the problem it solved.
V. Find out while the choice is still small
There's one more reason to do this early. A design decision gets a lot harder to question once it's everywhere.
When the same choice shows up on every page, changing it means redoing a lot of work, and people start defending it partly because of how much effort is already attached to it. A homepage direction is a manageable place to test whether we actually understood each other.
That takes some restraint on our end. It's tempting to show more because more looks like progress. A smaller review is usually the better investment if it lets the client react to the choices that will shape everything after.
I want the finished site to surprise people. I just don't want the surprise to be that we meant different things.