How to become a freelancer as Italian based in Italy

I am currently based in Italy and I have Italian nationality. I am a programmer and I already have a few clients who want me to work for them on projects. Since I worked normally in a 9 to 5 job until now and never cared much about Italian law and rules, I am now confused how to start this thing. Do I need a company, partita IVA or can I just write some bills for them? Or is it better to just leave Italy and go to another country where freelancing is easier to setup and taxes are lower (my clients don’t require me to be in Italy and neither does anything/anyone else).
Any freelancer from Italy here who has done this before? My question might be stupid or obvious to some, but any push in the right direction is highly welcomed.

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