Mario Kart 8 is out now on WIi U and here we have a short video from GameXplain which walks you through the simple steps necessary to unlock all 30 characters in the game.
You begin with 16 and getting the rest is pretty straightforward. To unlock a new character all you need to do is complete a Grand Prix race on any difficulty but you won't unlock a new character if you repeat a Grand Prix on the same difficulty meaning you'll need to play on numerous maps and difficulties to get things done.
Even so, it's easy enough to do. The video is below and you can also check out our guide on unlocking 90 stamps in Mario Kart 8 here.