Lonely I only know about men's prison's in England, so here's my advice.
Never borrow, never ever. You will either have to pay bubble (borrow one paper of baccy pay two back) or will be expected to repay in kind. Could be running an errand, holding drugs or stabbing someone. Do not shake on anything unless you are sure you can comply
Do not pilfer, steal or touch another prisoner's stuff without permission. Theives are universally loathed, ostrscised and will be dealt with by prisoners with no recourse to authorities
If he's in for years, as soon as he's moved to his 'home' prison (he might still be in a dispersal waiting on a settled placement) I would advise him to find out the requirements to become an 'enhanced' status prisoner and work towards it. It can help with a decent job (kitchen, library, medical orderly) and access to the gym.
Enhanced status can eventually help to get a room on the enhanced wing. Competition is fierce as EW is a massive step up in living standards in terms of environment. Curtains and bedding from Argos can be bought using canteen money in some prisons and there is sometimes ICE (in cell electricity, in the form of a plug socket which saves a fortune in radio batteries). It's a lot quieter than other wings and has a self regulating routine and code of behaviour.
EW are usually much more settled, most prisoners are on long sentences/lifers/white collar and work with officers to maintain agreed decent levels of 'neighbourliness' and accepted behaviour. Wing reps are nominated and voted in by the group in a democratic way.
Many are studying and they have wing agreed behaviours like no loud music, expected levels of personal, room and wing hygeine. If these are not complied with after a someone helps you get the hang of things, the wing commitee will vote you off and someone else from gen pop who is enhanced will get a chance.
Remind him about 'Listeners'. Listeners are prisoners who have trained with the Samaritans and can visit him to talk in complete confidence. They are a life line.
Sign up for church even if you are an atheist. Any time outside your room or off the wing is a bonus. Sign up for anything that gets you off the wing, litter picking in the yard, anything.
Sign up for any education - basic literacy and numeracy even if you don't need it. You may end up assisting the tutor with others who are struggling. Never talk about this outside the classroom.
This boosts your own self esteem and helps your reputation as being 'all right' or 'decent' and may be a help in sticky situations - for example, being hassled by someone, bloke you helped notices, comes over and diffuses the stuation. The bloke that struggled in class may be a 'face' on the wing and will repay the favour.
Finally, a note about time in the prison system. The prison system's 'soon' may mean two, six, 24 or 90 hours. It may mean weeks.
'Today' may mean this week, probably.
Here endeth the lesson 