If possible, take photographs of each house: the outside, the major rooms, the yard, and extra features that you like or ones you see as potential problems. And don't hesitate to return for a second look.
Make a difference by making a small change. Pelacing just the top 3 most used incandescent light bulbs in your home with Energy Star labeled compact flourescent lights can cut your annual lighting bill by a third. Although they may cost more to purchase, thay can save enough energy to pay for themselves twice.