What are best practices for finding, vetting, and working with freelance developers?

I’m planning to start a project soon and want to find freelancers for design and engineering work.

I’m hoping to learn from the wisdom of the crowd, and some of the topics that come to mind are:

• best places to look for freelancers/contractors (of course I’ll start here 😌😃 but where else?)
• how to screen applicants
• topics to talk about to ensure neither of us is having their time wasted.

What has worked for you?

If you work freelance, what makes a good client? What do you wish more clients did?

Thanks!