For me, a user of translations and also an ordinary man, who treats foreign languages only as a hobby, it won’t be difficult to answer this question. Communicating with various interpreters, who sell their intellectual work on the translation market, comparing CV’s, hobbies, and other different details, I’ve come to the following conclusions:

• A good interpreter has many dictionaries. It includes about 2 or 3 electronic dictionaries, installed on his own computer, and also a couple of paper dictionaries. And this is only a minimum.
• A good interpreter has friends – also good interpreters. There can be 1,2 or even 3 of them, whom he asks for help in case of need, and also whom he gives his own advice. (Of course, you can also ask questions on an internet-forums, on specialized sites, but when you need an answer right at the moment, a translator will appeal to his colleagues).
• A good interpreter has diplomas and certificates. He tries or has tried to pass one of the international exams or to gain knowledge from foreign teachers.
• A good interpreter, who has a master’s degree of the university, not only continues to absorb extra knowledge, inherent in his own profession, but involves double efforts in order to master, as much new and interesting information, as possible.