"Which side first?"

One of the favourite question my friends ask me for respiratory station. It's really depend on what you gather from the peripheral examination namely the tracheal position. If the tracheal is deviated, then I would advise you to concentrate on anterior chest first especially the apical region looking for apical fibrosis or collapse.
If the tracheal is central, then ask the permission to proceed with the back. The differentials would include fibrosing alveolitis, bronchiectasis, pleural effusion or consolidation.