Turn down the heat during the cold winter months. The warmer it is inside, the drier the air will be, making it less humid.
Fill a pan with water and place it on the stove. Turn the burner on, and bring the water to a boil. Leave the boiling water uncovered. The steam will create moisture in the air.
Open the bathroom door after a hot shower. Shut off the fan, and hang your wet towel in another room. The moisture from the towel, combined with the steam from the shower, will add humidity into the air.
Leave the water in the bathtub after taking a bath. As the water cools, moisture will be released in the air through evaporation.
Hang laundry inside during the winter. Water will evaporate from the clothes as they dry, releasing moisture into the air.