Best practices for finding and onboarding hardscape subcontractors -- what's working for you?

Hey everyone, I'm John, co-owner of McLutes in Austin, TX. We're a newer outdoor improvement company that coordinates landscaping, hardscaping, drainage, and outdoor living projects for homeowners. We act as the single point of contact so clients don't have to manage multiple crews themselves.

Right now we're building out our sub network specifically for hardscape work (pavers, retaining walls, outdoor kitchens, etc.) and I'm looking for input on what's actually working for people in similar situations.

A few things I'm trying to figure out:

Where are you finding reliable hardscape subs? Craigslist, referrals from suppliers, trade associations, something else?

What does your vetting process look like before you bring someone on for the first time? References, license checks, a trial job?

What do you wish you had locked down in writing before you started working together? Payment terms, warranty on work, photo documentation requirements?

How do you set expectations around quality and communication upfront so you're not chasing them down mid-job?

We're still figuring this out and want to build good habits early rather than learning the hard way. Any lessons from the field would be hugely appreciated. Happy to share back what we learn as we go.