“My double storey terraced house has two front doors. One is a wooden door and the other is a sliding glass door with aluminium frame. Both doors open into the driveway. For the good of FengShui which door should I use, should I use one or both doors?”
One of the basic principles in FengShui is that a door as the mouth of Qi into your house the size of the door must be proportion to your house size. If your house is large, your main door must be big enough and if your house is small it would be better to have a smaller door. Since your house is a terraced house, in general it is not good to use both doors as this will cause too much Qi to flow in. You should stick to your smaller wooden door and keep the sliding door closed.
However you should also consider the facing direction of your door. If both directions are auspicious then stick to your wooden door. But if your smaller door is inauspicious you will need to use the sliding door. If your sliding glass door is huge, try to cover some area with curtain or blinds.