Hacking the impostor syndrome
One key thing for all managers to avoid, but especially for accidental managers, is what technologist and writer Peter Gillard-Moss calls imposter syndrome. This is when an often newly promoted manager feels compelled to show that they know everything, even when they don't.
When imposter syndrome sets in for a manager, an array of negative behaviors and impacts can result, including becoming ever more insecure about your position of responsibility and alienating your own team because you're killing their motivation to collaborate and be creative. Not to mention that the manager is stressing themselves out by trying to stay on this treadmill, which only goes faster and faster, even if they're still going at the same speed. The most common way to be a victim of imposter syndrome is to believe that your superior technical ability and/or experience entitles you to be a manager and to lead.
A simple hack to avoid imposter syndrome is to recognize and admit that there will always be things you don't know and aren't even aware that you don't know! This is what makes the journey interesting, and you should never be in denial that there is still so much to learn, no matter how much you think you already know.