I would say the Herald would definitely be the best starting point.
Glasgow is very varied in the quality of areas - like any other city - but the intermingling is rather greater; street to street, almost. He would be very well advised to have a good look on the ground or at least ask people.
Depending where your friend is working, the Merchant City would be a good possibility, otherwise the West End or Park. I would only suggest south of the river if that's relevant to work - there are some very pleasant areas (Pollockshields, for example) but most of the life of the city is north of the Clyde.
(Apologies to any South Siders for any offence but, really, it is a bit suburban... and yes, I know that's rich coming from someone living in Ayr )