The first steps a new team leader should do are:
Learn the set-up. Get to know who is who, and what is what.
Find out exactly what the goal is.
Find out exactly what the current plan is.
Integrate yourself into the current setup, without making waves.
Then, once you settle in, look for ways to improve the current system.
When you find such an opportunity, then take it.
Ultimately your job is to improve the system. If you do that for the rest of your career, then your future prosperity will be assured.