How do you get your first real customer when starting a clothing brand?

I’m thinking about starting a small clothing brand, but before I jump in, I really want to understand one thing:

How do you get that first real customer, someone who isn’t a friend, isn’t family, and doesn’t know you at all?

If you’ve done this before, I’d honestly appreciate your insight:

• What genuinely worked to get that very first sale?

• What did you try that ended up being a waste of time?

• Anything you wish you could tell your past self before you started?

Just looking for real experiences from people who’ve been through it, no viral fairy tales, just the truth.