battery Lithium first charges

Hi everyone,
I just got a new Dell XPS 15 in order to set arch on it (should be linux friendly). But I am confused on how managing the battery. I haven't touched the laptop yet.
I guess I have to full charge the battery and then?
Is it better to discharge it totally or stop when I get 20 or 35%?

Please, could you explain me how to manage a Lithium battery for both the first cycles and for the lifetime?

Thanks for your time.