Just a few personal lessons here, recording for my own reference. They're not things I didn't know before, but they've been hammered home strongly the past few months.
Hiring is the most important thing you do as a manager. And every new hire must raise the bar. This is an Amazon principle, but it's universally applicable.
If you're unsure, pass on the candidate, or add an extra interview step to provide more certainty. Hire only when you're very confident that this candidate will be a bar-raiser.
When a good hire joins, it raises morale and productivity across the whole team. Likewise, a bad hire is a wet blanket on the whole team.
You'll make some. Hopefully not many, if your bar is high enough. But when you do, own it. They must be given direct, specific feedback, very quickly. If they can't turn around quickly, you must let them go within their probation period. The question to ask, regularly throughout the probation, is "if I could just re-wind time, would I hire them again?" If the answer's no, they can't pass probation.
Letting someone go sux for everyone - you, your team, and most of all, the person being fired. If you're doing it more than "very rarely", it means your hiring bar isn't high enough. You still must do it! But raise your bar to prevent it in future.
Not just for new hires, but for everyone. If a manager has negative feedback for a report, it must be delivered quickly. Don't wait for next performance review. And usually, don't wait for next 1:1. The feedback must be direct, specific, empathetic, and framed in the best way to allow the report to quickly change and grow.
You must lead by example on delivering feedback to this standard; culture filters down from the top. It's scary at first, but most people - either immediately, or at least later upon reflection - appreciate the honesty and opportunity to improve.
Likewise, positive feedback is easy to forget about (if everything's going well, no need for feedback, right?). But it's equally important. Positive feedback must be specific and heartfelt. "You're doing a great job" isn't good enough - what exact thing are they doing well, and what good outcome is it creating? Why do you truly appreciate them doing it? Let them know - and usually, do it in a public channel so they know the team is aware of their effort, and so the team knows what "doing a great job" looks like to you.