Ask HN: How do you conduct conduct one on ones?

I'm curious how different people go about conducting 1-1s. How are you going about it and what exactly are you looking for? How often do you think is best? I swear I read a good blog post on this once but I cannot find it.

I am fairly junior in my career so I have only experience a handful of direct managers. My manager recently moved to a larger company and we are looking to fill his position. I think 1-1s are vital, so I want to make sure whoever takes the role will make the most of the opportunity.