So use solar sails attached to transport ships carrying some other materials to mars. Once the ships enter orbit, detach the solar sails and manuver the sail material (probably mylar) to Mars's L1. Use the solar wind to keep them in place, and balance that with the gravity of mars and use that to refract the solar radiation hitting Mars until it equals that of earth. That would increase insolation and generally supply more solar radiation to the surface of mars. Once the extra heat is added, it will sublimate the CO2 in the soil/poles and increase the greenhouse effect and start warming the planet. That would also increase atmospheric pressure, making habitation easier to achieve. Granted, the new air won't be breathable, but who cares! The planet will be warmer and the atmosphere thicker. If, at some later date, we wanted to make the air breathable, then some serious CO2 scrubbing would be required, but still. That could be a long term goal provided by seeding the planet with.. um... plants! Let the trees do the long term work.