Apply for places to study translation. Translation is usually taught as an Master of Arts-level subject, and candidates require a degree in languages or a background that demonstrates considerable linguistic ability. You may also need to take a translation test.
Improve the language from which you wish to translate. Typically, you will already have excellent language skills if you are accepted into an M.A. translation program. Bear in mind, however, that your language skills will be put to the test, so get sharp before you start.
Expand your source languages. The more languages you know and translate from, the more opportunities for work you will have after graduating. If you are strong in one language, but weak in the other, try to improve your weaker language. This will leave you well prepared for the M.A. course.
Improve your English. This may sound strange, but your English language skills will need improving, too. You will be translating a wide range of texts, so familiarize yourself with the range of registers available. Read articles on subjects you wouldn't usually look at -- for example, economics or law, in quality publications. This will keep your English language mind sharp and eloquent, ready to write in the correct style.
Avoid common translation pitfalls. This may mean writing something too close to the source text, missing sections or words or mistranslating phrases. This will improve by talking to your colleagues, evaluating your performance and practicing.