Make sure you set the difficulty to Expert before attempting the points challenges, as you just won't be able to accumulate enough points in lesser difficulties. When playing, try to wake up as many ghosts as you can while collecting pellets, so you can get more points when you start eating. It is pretty hard to die as the game slows right down before any impeding collisions with ghosts. The may take a couple of tries as if you die you will struggle. Remember you can use bombs to help if you get stuck in a tight spot!