Hello
As previous posters have said, get an electric razor. A three headed one with a trimmer on the back should suffice. Also, consider one that is rechargeable. Most bathrooms have a two pin socket for charging them (similar to an electric toothbrush). You can spend a fortune on electric razors, but you should be able to find one...I would stay with the well known brands, either Braun or Phillips.....I've also linked one here
Philips Electric Shaver 3000 Series - Wet & Dry Electric Shaver for Men with SkinProtect Technology in Dark Moon, Pop-up Beard Trimmer, Cordless Shaver (Model S3145/00) : Amazon.co.uk: Health & Personal Care
As for wet shaving, this has advantages and disadvantages. It provides a much closer shave than an electric, but takes longer to do. It also exfoliates, but can irritate skin, esp if he suffers with acne.
Once you have got the main bits, the biggest outlay with wet shaving are the blades. They can be expensive, and the only way to find out which ones suit best are to try them. Gillette and Harrys are popular, with the blades available in most large supermarkets.
With wet shaving, the idea is to reduce friction, which can irritate the skin. I would recommend wet shaving in the shower first....this allows you to soften the hairs (as they get thicker with age) which makes shaving easier. I would always use a shaving oil...link below
Pre Shave Oil – Murdock London
This will last about six months, as you only need a small amount. Rub this into the beard for a few minutes before you start to shave.
I would also recommend a decent shave cream....I use Body Shop, as it lasts for ages, and is relatively cheap compared to some....link below...
Aloe Shaving Cream | Maca Root Shave Cream | The Body Shop
Body Shop have offers on so you can save money if you look. You only need a small amount of this when you shave, and again, rub this in well before you start to shave.
Both the oil and the cream together will reduce friction and hopefully provide a quality shave.
Hair on your face grows in different directions, especially on your neck, so it's worth advising your son to spend time when learning to shave. Some advise to always shave in the direction of the hair growth (for example, if you shave your legs, shaving down towards your feet is with the growth, shaving away from your feet is against the growth) but I have no issues with shaving against the growth. This will depend on you son's skin type and how thick the hair on his face grows over time. He will soon see which option works for him.
He could also moisturise after shaving if this helps with his skin, but please tell him never to put/spray aftershave on his face.....think of Kevin in Home Alone!
I hope this helps......