Since we can't be everywhere at all times, much less know everything, we need to rely on sources to translate accurately. Thus, we need to seek a model, be it spoken or written. The most obvious is the dictionary, but what does a dictionary provide?
You might answer "definitions", and you'd be right in part. The only problem is that aside from the meeting of the word given by dictionary, there are aspects that simply fall through the cracks. After all, when we speak, on the one hand, we try to say the same things that mean roughly the same. However, there are always interpretations, always usages that are regional, or, as it happens in my work, specific jargon. Nonetheless, I believe that a good dictionary or glossary is a good place to start because it was compiled and edited by specialists employing true and tried techniques.
When translating Spanish to English, I go straight to the Real Academia Española, which is an official body that regulates the use and usage of the Spanish language. I know that the French also have a similar academy. Not so with the English language. Perhaps the Oxford English Dictionary in the Chicago Manual of Style to be considered as stand ins for a formal body.
When I come across Spanish that I just can't find in regular dictionaries and glossaries, I turn to the ProZ.com term search. The accuracy and validity of search results can vary widely. If I didn't know the general meaning of these terms, I would be wary in selecting just any old answer.
As for a general style, for both language learning and translation itself, I have devised a system whereby I use at least two sources to determine how I'm going to translate certain texts. Now, I almost always deal with standard English, so I don't have to worry too much about slang or dialects. As you might imagine, that does not let me off the hook, as there is no way that I can be proficient in all aspects of English language usage. There are always two or multiple ways of phrasing things. One is not necessarily right and the other wrong, but it is important to be consistent.
To hone my overall style, I follow someone I think speaks or writes well, like a teacher or television commentator or world leader. I make a note of what I like and try to incorporate it into my style. As for reading, I usually take section is an example, and look for someone who writes short, concise sentences that are neither crowded with nor empty of meaning. I also look for cultured, but not pompous words. This is important, because most translations are geared toward everyday people, not an academic elite.
Getting back to my Proz searches, when it comes to a live version, I talk to people who are in the know, but I try to talk to at least two, and hopefully more. Each person potentially has a different take on a term or phrase. They could all be right, but then again one of the definitions may not suit you. You also have the advantage of someone who lives and breathes the language. I did this when I was learning Spanish in Costa Rica, and it really reinforced my knowledge.
If you're not already doing it yet, why don't you give it a try and let me know how it goes?