What are the characteristics that make a good engineer?

You need to know your subject and be disciplined. Good intention isn't enough if you create and build failures. You need to know how to communicate with others and get things done in a team environment. If you get into engineering management you need to know how to lead and motivate others and how to juggle many things at one time, including budgets. Finally, you need to be willing to constantly learn new things as technology is always changing.