6. Keep things fresh. A house that looks clean should smell clean, too. Cooking smells, mildew, pet odours - they're all serious turnoffs. Open the windows, use air purifiers, put out some lightly scented candles. But be careful about using plug-ins, room sprays or other artificial fragrances. A lot of people are sensitive to them, and having an overwhelming scent can make it seem like you're trying to mask an odour problem. Less is definitely more.