It is good Feng Shui to reduce Sha (negative energy) when using paving, by avoiding the use of overtly straight lines. Curved paving stones are best, but straight-edged paving stones laid in curved lines or a herringbone pattern will help break up the edges and encourage Chi (positive energy). If you have a large existing paved area which is impractical to re-lay, the carefully placing of a table and chairs or plants according to Feng Shui principles will enhance the Chi flow.