Well done - give positive feedback often. Be generous with your praise, profligate even. In giving praise, be as specific as possible. 'Well done. Your presentation was well-designed, your delivery was engaging and you answered the questions concisely. I particularly liked the way you used your hand gestures to underline the three key points.' Everyone likes praise - it raises our self esteem and reinforces a positive image of ourselves. It also means your team knows you recognize their efforts and value them. You should wear out the words 'well done' - they never lose their value and you have an unlimited supply.
Please / thank you - just like your mother used to tell you. Imagine that your team are all volunteers. They could work anywhere (and they probably can). So ask politely when you want something done, and thank them when it's been delivered. Too many managers assume their team is there simply to do their bidding. Don't be one of them.
I am sorry - lots of things will go wrong when you are a manager. Many of them beyond your immediate control. It doesn't matter - you have to own them, sort them out and apologize. Many managers see it as a weakness to apologize. They never admit fault. The implication is that mistakes are everyone else's fault. This won't win friends or influence anyone. Instead, put your hand up and own the issue. Apologize quickly and move on. It'll cost you nothing and have a huge impact.
It may sound basic, but if you use these eight words frequently, you'll be amazed at the impact they will have on your team. Who knows, they may even say 'well done' back?