A way for a team to get better is by working together more. Some people are really good team players but some on the other hand are not. Like everything else in life working as a team takes practice. You just have to work together away before you can get the three main things to be a good team which are trust, working well with each other, and being honest like I stated before.
A team is successful usually when there is a common goal and the whole team strives for that goal together. No matter if it is sports or student council a team is only as strong as their weakest player. So making sure no one is left behind and the goal gets completed is the main thing that makes a team successful.
There are many different ways to turn an unsuccessful team into a successful team. One way is motavation. I know in highschool when my dance would not be doing so well in practice and at games, we thought we were unsuccessful. When our coach would give us motavation, which usually was something along the lines of saying other schools dance teams look better then us. It really helped us because we would try to prove people wrong and we became a successful team and finished out our year very strong.