Good evening i want to ask what is the perfect way to keep my battery save for a long time ?

Batteries will wear out. That is expected. There is no "perfect" way to keep them from doing that. deggie told you everything you need to know. The rest is details.

If you want those details, see this article:

When to charge your iPhone or iPad - Apple Community

Don't use it in temperatures that exceed the specifications, don't let it become fully depleted.

Good luck!