Focus on what you can control
You can do anything, but not everything. - David Allen
Especially when you start your leadership career it's normal to think you should be tackling everything at once. But the only thing you will accomplish by trying that is disappointing yourself and your team.
Instead think about what you are able to influence directly and start there. By improving what it in your control, you will slowly but steadily influence people around you (remember the environment from the basics, you are also someone's environment).
And by doing this, you also widen your circle of control.
But especially for the beginning, be aware of what you can control, and what not. It's handy to have a list of what's under your influence and what not. It helps you be aware of what to touch and what not.