I believe the first job of any arts marketer is avoiding disaster. Marketing can't make art a "hit". Only the art can do that. But I've learned from experience that what effective marketing can do is create a ticket sales/audience attendance baseline that can give the art the opportunity for success.
So when I'm working on a project I start with a pro/con list and then I ask:
What's the floor?
Meaning what's the minimum amount of sales that we need in order to make the top end success, what I call the ceiling, possible?
There are a thousand ways to figure out your particular floor. When I'm working as the marketing director at my theatre I use a 20/40 benchmark, meaning we want 20% of the ticket sales projection by the time the show opens and an additional 20% (40% total) by the time the press arrives to review the play.
Does hitting those benchmarks promises success? No. It secures a decent floor. 60% of the ticket sales can still be influenced by future marketing efforts, reviews, words of mouth, etc. All those things create the ceiling.
Again, that's my way of defining the floor. It's very situation specific so you may define it differently for your work. But it's important to remember the principle here which is that marketing can only do so much.
Don't get me wrong. It can do a lot. But it starts with reasonable expectations. It can lead to outsized results.