For the black, by hand. Wash it thoroughly first, then dry it, Polish it up with the Autoglym Black label stuff, and then wax it with Poorboys Nattys, using a cotton covered foam applicator and a really soft plush microfibre towel.
Being a VW it will have really hard paint, so you may need to give it a few coats of polish. As what prevents a deep shine is swirls, and your very unlikely to remove those by hand, but Natty's is a sealant wax which will fill them to mask them
When washing it, don't use cheap carplan stuff (as crappy shampoo will wash away the wax), use Meguiars Gold Class with a woolen wash mitt, it seems expensive but you need so little it will last ages and is actually good value for money. Then dry it using a Quick Detailer spray on a waffle weave towel - this will top up the waxed look.... not somethign I do often in the winter, but i do from Spring onwards.
Interior, whatever you use, there are 1000's of ways. I like the foaming sprays that you scrub in & then let dry, but id rather work on leather.