Tips for a good opening message?

I'll admit I'm not great at this bit. Tend to either write an essay or just say hello and nothing else, neither of which seems to land particularly well. Any advice from people who do this better than me?

Mention something specific from their profile rather than a generic hello, makes it obvious you actually read it. Doesn't need to be long.

This. A proper question about something in their profile works so much better than hey how are you.