Tree planting is important, but with the movement of pests into areas previously free of them (e.g. the pine bark and spruce bark beetle infestations in Canada) means that foresters and other arborists will have to consider carefully what they can plant that will fix the most carbon in the new conditions. (Restoration ecologists have already considered how restoration ecology must change in the face of this changing climate.) This will also require those who previously depended on wood for various uses to find other materials for those uses.
Taking steps to protect fresh-water resources is another essential step. Here, the goal should be to ensure that rainfall isn't wasted, that aquifers aren't exhausted (which can lead to subsidence and to contamination of the remaining fresh water with nonpotable water, most commonly salt or sulfur-contaminated.) In warmer climes, surface water storage of the current type will not be sustainable over the long haul (published data on evaporative loss forty years ago on some stations on the Texas Mexico border exceeded 100 inches/year--in an area with average annual rainfall in the low 20 inches.) Conversion of unsustainable agricultural lands in semi-desert areas to sustainable native vegetation should be considered; get healthy short-grass going before things get worse, and it might be possible to retain some non-irrigated food production via low-intensity grazing. Support of agricultural lands in ways that make them more sustainable (and thus often requiring less water for crops.)
Switching from high-carbon energy sources to lower-carbon ones would also help.
Population stability will be necessary some time in the future--we can't provide equitable living standards for the entire world population now, and should reduce population to the point where that is possible. We waste human resources now to a scandalous degree--worse than wasting petroleum or coal--because we cannot provide the living standards necessary for everyone to achieve their potential.
These are only a few general suggestions--there are many more, and specifics for each individual in any situation (urban/rural/suburban/wealthy/poor, etc.) but though it would've been a heckuva lot easier to make changes 30-40 years ago...and 20 years ago...and even 10 years ago...we are where we are.