Even as we colonize the Moon we should begin to develop plans to colonize Mars and/or near-Earth asteroids. By colonizing the Moon we will be able to reduce costs as well as counterbalance costs with mined minerals and derive new energy supplies from space or lunar surface solar panels deployed on a significant scale.
Colonization of asteroids will likely depend on whether important minerals can be found here. It seems as though such objects may be mostly by-passed unless there are significant finds made after preliminary expeditions. Small outposts may be established and expanded when minerals can be mined when they prove to be worth the effort.
The major immediate effort after the Moon will be most likely to establish outposts on Mars. This may not come until toward the end of the century when efforts to terraform the planet yields a significant re-establishment of plant life and a rebuilt atmosphere on Mars. Such efforts may be well underway but mid cenury. As in the case of the Moon, large solar panels may provide more than enough energy for early expeditions and an establishment of moderately large human colonies after a time. However, it is unlikely that these expeditions will be led by the faint of heart. Colonization of the Moon and Mars will likely still be an adventure through the middle until toward the end of the next century.