What are the methods should be followed to become a professional translator , specially with Russian language?

Russian as a source language:

Russian are usually not exposed to different languages in their daily life: TV, mobiles, websites, songs, everything is Russian! So you should start by getting exposed to other languages in written and oral forms the best way is talking to a native speaker and reading.

Russian as a target language:

as mentionned above speaking to a native Russian is the best you can do, if it's not an option listen to Russian news or Radio, the positive side about this language is that it doesn't have a lot of slang so you can master a good part of it just by learning the official language.

Everyone who is dreaming to be a professional translator need proper grammar base. Does this sound boring and academic? Yes, it requires a lot of intellectual efforts but this is an only way to be a professional one.