I think the most important aspects about global citizenship are human rights and nationality. Human rights are shared by all humanity and thus they ignore the differences between cultures and focus on the humane aspect that unites us. Nationality is a big part of one's identity, but if we start thinking of it as superior to others so we experience ethnocentrism, then we need to change our attitude to become the global citizens and to think of ourselves as citizens of the world. If a person goes to work in another country that he/she views as inferior, he/she will not be able to reach their full potential of success, unlike if they see that they are rather giving back to humanity. Global citizenship calls for equality and believes in humanity.
Some of the assignments/ lectures that helped me learn about global citizenship: