Sequel Month - Editorial - What makes a good sequel?

Yeah, I know this was supposed to be a Doctor Who review but I was kinda busy so I'm just chucking something together to get something out in the morning

It's sequel month

And whilst the Nostalgia Critic asked why sequels are bad, I'm going to go against type and ask a different question, what makes a sequel good? Because this is rushed, I'm going to talk mostly about this in general rather than referring to lots of examples.