There are lots of official procedure from filling up a visa from to getting a proper visa. And Document translation is one of the most important aspects of visa approval; only when your documents are not in the language of the country you are apply for visa from. Suppose, your documents are in Arabic, and you are planning to visit German, Australia, France etc, then the concerned embassy may ask you to provide a certified translation of the required documents. For example, your passport, your bank statement, your address proof, police clearance certificate etc.
However, you should make sure that the documents translation you are going to submit must be certified by a translation agency, which gives the authenticity of the translation and gives the statement that the translation has been done by a qualified and experienced translator.
There are lots of translation agencies and translation service provider offering document translation services. You can find most of them online. Before submitting your documents, talk to them on phone first and ask about the prices and deadline. If you have a short deadline then do not rely on a single translation agency.
Contact different translation agencies and ask them to deliver the translation within the speculated time. Moreover, you should make it clear that you will not be able to proofread it, so you want a complete translation with proofreading and editing.
Before the final version or hard copy of the translation is finalized, ask the concerned translation agency to send you a soft copy to make sure that your translation is ready. It might be possible that you do not know the target language, but still you can match the lines and sentences and some numerical with the source language. It will help you to find major problems in the formatting.
If you have any doubt about the translation then you can write back to the agency to make everything clear.