It's not perfect, but I use baby wipes to clean off the worst before I head in. Don't have running water in the shop so to avoid putting black fingerprints everywhere, it's good enough. Also much cheaper than specialized wipes. After that, ordinary soap usually does the trick.

Dish washing liquid is better than ordinary soap I find, but rarely necessary. A specialized product with something grainy in it is better when you're really dirty and it's on there good.