Nobody enjoys the ribs. Here is the rest of it, without pretending.
Eat a real meal beforehand, not coffee. Bring something sugary for the third hour, which is when most people dip. Sleeping well the night before matters more than anything you can do the day of.
Do not drink the night before: alcohol thins your blood and a session that bleeds is a session where the grey does not sit properly. Say when you need a break rather than going quiet and rigid.
For most people, the ribs and the sternum: thin skin directly over bone that moves with every breath.
The outer upper arm and the outer thigh. Both are muscle with padding, and both are good places for a long first session.
It works for a while and then wears off mid session, and some formulations change how the skin takes ink. Talk to him about it beforehand rather than showing up already covered in it.
The area is often more sensitive if it has not fully settled, which is one of the reasons for leaving weeks between sessions.
Requests go straight to Federico, not to an agency inbox. He answers from his own address.