If possible make him an indoor pig, certainly get him a companion. They are social animals and need the company of their own kind. Humans are not guinea pigs!
There is a lot of rubbish talked about putting pigs together, eg litter mates don't fight, never put an old pig with a young one etc.
There are two "rules"
Male and female together will attempt to breed.
I do not agree with neutering a male just to put him with a female
Secondly, and probably more important, is to try him with a companion and see how it works out. You may find him a suitable friend straight away, if not try other pigs until he finds one that he gets on with.
Neutering boars to "stop them fighting" has no basis in fact. Neutering has no effect on aggression levels and is a waste of time and subjects the pig to unnecessary surgery.
It is well worth the money to buy either of the books by Peter Gurney about guinea pigs, together with his book "Piggy Potions" which gives a good guide to pig ailments and problems.
It is a good idea to find someone in your area who knows about guinea pigs before if/when they become ill. Vets are not always the best people with guinea pigs.
Contact the Cambridge Cavy Trust tel; 07721026401 for further advice on people in your area who can help.