Purchase prefabricated external blinds made out of shade cloth. They are a relatively inexpensive solution at around $200 per blind. Hung externally from a fascia board or verandah they will help keep the hot summer sun off windows and walls.
Purchase prefabricated shade sails and install them strategically to effectively shade walls and windows. Alternatively, buy shade cloth in bulk and sew your own blinds or even build your own frame and attach shade cloth to protect north, east and west facing walls and windows. A common DIY option is to hang shade cloth or sails from the fascia to the edge of a fence (check with your neighbour first).