The original way to unlock this achievement was to use a tank with a single crew over and over again until the crew reaches rank three. Without XP boosts, this could take 300 matches or more. You'll want to pick a tank you do well with, and use every XP boost you can find.
If you've earned this on the Xbox One, it should unlock immediately when you get to the garage. If it doesn't, finish one match with your crew of rank 3 or higher. Starting any war story on Xbox one will earn this. Try the first American War story to unlock a crew that's already Rank 3. You can transfer the crew to any premium tank of the same nation and use it in a Xbox 360 match. Also on Xbox one, Many Mercenary contracts will also include a Rank 3 crew.