I like to consult The Encyclopedia of Literary Translation into English, which reviews most, though not all, translations of many well-known authors, including Kafka, and can give you an idea of some of the merits (or, I guess, also demerits) of the existing translations out there (up till 2000, at any rate, when the book was published).

If you'd like to get up and running quickly with German in a basic sort of way, I would suggest also taking a look at The Berlitz Self-Teacher: German.