Low pressures, a lack of oxygen and cold weather on Mars would force humans to remain confined to spacecrafts and vehicles, according to physics.org. Astronauts could occasionally walk around in the open, but only if they wore spacesuits. Settlers would risk dying if their spacesuits became seriously damage. Underground shelter would be an ideal scenario. As of 2014, no settlement on Mars has been established.
Settlers would first need to set up an energy source, either solar or nuclear, that would be used for the essential tasks of extracting oxygen from carbon dioxide and water from hydrated minerals. Astronauts would arrive on the planet with 15 days of stored water. The water would need to be recycled and stored and could last for 150 days if properly conserved. A device similar to a portable greenhouse would be necessary for growing food. Settlers would also need workout machines to prevent body degradation from the zero gravity.
Ideally, Mars would undergo terraforming, which is the process of creating atmospheric conditions that are suitable for life. For instance, if scientists added carbon dioxide to the atmosphere of Mars, it could cause a boost in air pressure and warm up the atmosphere by way of greenhouse gases, which eventually could lead to a more hospitable habitat.