The first colonists to Mars wouldn’t go in "cold." Robotic probes sent on ahead would establish necessities such as an energy source (such as a small nuclear reactor augmented by solar panels), enough food for two years, the basics for creating home-grown agriculture, one or more rover vehicles and a tool-kit for carrying out essential engineering and maintenance work. In addition, the scientific equipment needed for the colonists to do important research work should be part of the preceding unmanned mission. All this equipment could easily be put into place using current technology before the astronauts set out. The first human contingent would rely heavily on resources that can be produced from Mars such as water, nutrients, and shelter (such as in form of lava tube caves). They also would be continuously resupplied from Earth with necessities that could not be produced from the resources available on Mars. This semi-autonomous phase might last for decades, perhaps even centuries before the size and sophistication of the Mars colony enabled it to be self-sustaining.
The first human contingent would consist of a crew of four, ideally (and if the budget permits) distributed between two two-man space craft to allow for some mission redundancy such as in the Viking mission or for the Mars Exploration Rovers.
Why would we want to colonise worlds which are inhospitable? I could be wrong here, but wasn't there something on the news about the Moon having water? This might seem strange, but we (and most other life here on earth) require water as a basic necessity to survive. The biggest growth of habitat on planet earth is desert- i.e. a place without water and many millions of people live in these places. Thus water could become the 'black gold' of the 21st century. Perhaps this might give people motivation to colonise moons or whatever. 
