Hi Giuseppe,
As amoun says there’s a lot of good advice on the forum.
Patience is very important.
See the guide article which is also a good starting point. I recommend you to read it and maybe follow up some of the more than 20 topics that link to it …
If you need help testing modules you might be able to get in touch with a fairphoneangel or another Fairphoner in your area who has a FP3.