Check with your embassy or consulate and other expatriates about which areas of town are safest. Most houses are built with perimeter walls or fencing, some with spikes, barbed wire or glass shards set in the top to discourage climbers.
Most people employ security guards at night from a reputable security company (See below). It's not a bad idea to make sure the guards are awake at various times during the night. Outside or perimeter lighting is also recommended, and guard dogs are often the best security because their bark may wake you in case of an intruder.