It would be a good idea to practice assessments online. There are several good ones which other guys have already mentioned in this thread. I even bought a joystick to practice... It was fun. Answer honestly when they ask about your personality, and basically no matter what they ask, just don't make anything up. After that, if you pass, you will have the interview with the people from Wizz - you should probably wear a suit and tie, smile, be friendly, have all the soft/people skills. Just try to 'sell' yourself the best way possible.
Good luck!