Use good quality butter and make sure it is as cold as possible before starting. I like to cut mine into little cubes on a plate and freeze for about 10 minutes. Do not incorporate the butter into the flour until it becomes too small. You want those larger pea sized chunks that will help create flaky layers. Do not overwork the dough. Make sure you handle it as little as possible to avoid melting the butter too much and overworking the gluten. Do not add too much water - only add enough to help the dough together. It is important that the water is very cold and has pieces of ice inside. Fold the pastry right before refrigerating. This will make lots of layers in the pastry. Make sure to handle the pastry as quickly as possible, keeping the pastry that you are not currently working with in the refrigerator.