I remember when I was a beginner translator under training in one of the most prominent newspapers in Egypt. One morning, the head of the translation department asked me to translate a very complicated medical document. Having a first look, I felt like I had no idea what was the author talking about, but after reading again, and again, and again...I finally felt a sense of the author's meaning and suddenly knew where to start and how to put into the the proper target language. It took me the whole shift and late into the evening to finish it. Before I left for the day, I put the translation on the boss’s desk. It was quite late already and everyone else, including him, had gone home. The next day, my supervisor called me into his office making me wonder what kind of a mess I had made of things. Imagine my astonishment when he asked me what medical school I had graduated in. After I recovered from my complete shock, I smiled big and answered, "Sir I have never studied medicine.”
At the time, given my beginner status, I was not yet able to put into words or give labels to the qualities necessary of a professional translator. As a novice, I was certain that mastery of the target language was the primary skill required of me. However, the years have taught me that professional translating is much less of the technical science that I first believed. Instead, I began to view it as a fine art. Each original text is a masterpiece in its own deserving of the utmost reverence. Not just the words, but also the meaning of the author must be discovered and related by the translator before the job can be considered finished. To accomplish this, the translator must dive deeply into the work and taste it so thoroughly so as to completely understand the author's intent, regardless of how easy it may, at first, seem or how familiar it may sound.
Regarding the technical and scientific aspect of the professional translator, I subscribe to the belief that the standard of good translation is to lead the reader to believe that the translated text is original and not a work with beginnings in another language. For example, if the text is a legal document, the reader must feel that an experienced lawyer has written the document. If the text is regarding medical issues, the reader needs to feel that it was written by a well experienced medical professional in that particular field of medicine. This is true of every document regardless of its content. First and foremost, this requires the professional translator to have mastered not only the target language, but also the source language of the document. In fact, it can be argued that before mastery of the target language can even be attained, he/she must have mastery of the source language. This was one of the most unforgettable pieces of advice imparted to me by one of my favorite professors while I was still studying techniques of translation... He explained...
One must first master his own native language (i.e. grammar, structure, parts of speech ... etc.)

Using specialized tools (dictionaries and CATS) is another factor to help on producing a professional standard of translated texts. But again, the dictionary cannot read the author mind, only you (as a professional translator) could taste the text and to convoy the meaning the author wants to pass.