Just want to share about my experience in teaching Java..
I used to teach Java when I was still studying in my university. One of the main factors that could lead you to be successful in teaching is
you should know the programming level of your students. You should know whether they have previous programming experience, what programming language they had learned before. If they learned C++ or other OOP, it will be much easier to you to teach them the basic of Java. If not, you have to teach them the basic of programming first.