When you have to get the ingredients for snape go down to Hagrids hut. Then go up up to the greenhouses and talk to prof. Sprout. keep on fighting battles and after each one go and see prof. Sprout. When she gives you a house point go back to hagrids hut and the back to prof. Sprout. Keep on doing this and talk to prof. Sprout each time and she will give you a house point each time too.