great question. weeding out people up front that are not team players and job hop goes a loooooong way. once you immediately root that out the rest of it:
The compensation one is the one that most companies get wrong for retention. It seems most companies say they're "competitive" (within some unspecified tier). And they may be at hiring time, but a frequent complaint is that companies don't keep the compensation competitive. (Netflix famously being an exception.)
How do you handle retention, once you "marry" an employee?
If the manager retired, would the company keep nurturing that?