Good managers usually learn by having bad managers themselves. They see what to avoid.
First, don't be overly controlling. Micromanaging, creating impossible rules--these are bad.
Admit mistakes you make them. Hanging tough makes you look lame.
Don't send mixed signals. Set a positive tone.
Don't punish the good and reward the bad. Sometimes managers are intimidated by talented employees and give them a hard time. Don't.
What do you think? Do your hires look forward to coming to work?