Pay good money. Moreover, provide meaningful raises as experience and expertise increases, and in line with the external job market. Don't hire in new hires above the salaries of your experienced employees that have to then train and babysit the new folks for six months to a year and clean up their messes.

Provide a private workspace (ideally private offices) where your knowledge workers can do their job without distraction. Don't cheap out on equipment and tooling and learning materials - it's moronic to quibble about buying an SSD or a monitor or a piece of software or a book that costs a couple of hours of your employee's hourly rate.

Provide clear direction, without micromanagement or silly infantile circle-time processes. Don't engage in ad-hoc walking-around status checks, don't demand immediate responses to asynchronous communications. Don't waste time in superfluous meetings.

Don't vacillate or chase after every customer request. When one of your employees says that something is unwise, and provides solid reasons, listen, and don't go around them to find a stooge who will obey your whims and slag in a big pile of technical debt.

Don't try to push any culty workplace culture stuff. Treat your employees like the highly paid professionals they are. Respect their time and other obligations.