Don't forget about your plants light requirements. Even houseplants need light, and most prefer well lighted locations. Light provides the energy source necessary for plants to manufacture food. Plant light requirements are usually measured in foot-candles. Most homes are full of areas that are too dry for plants.
Plants often thrive in kitchen windows and brightly lit bathrooms because of the humidity.
If you suspect that your plants are suffering from dry air, set your plants on trays filled with gravel. By filling these trays about half-full with water, you can maintain an air gap to ensure good drainage, and moisten the air around the plant with evaporation from the water in the trays. One last word of caution, be careful not to move insects indoors with your plants. Insects love to stow away on potted plants, and once they get inside they often thrive because there aren't any predators. Use a weak solution of household detergent and water to clean plant leaves, then thoroughly inspect your plants.