Dampen a washcloth with water and wring out the excess. Place two drops of your favorite fragrant essential oil on the cloth and rub the washcloth together to distribute the fragrance.
Lay the shirt on a flat surface. Gently rub the scented washcloth over the shirt, paying special attention to any areas that smell, such as under the arms or around the neckline.
Turn the shirt inside out. Fill a spray bottle halfway with white vinegar. Add water to fill the bottle. Spritz the shirt with the diluted vinegar spray.
Place the shirt on a hanger and hang it outdoors for a few hours. Fresh air is very effective for removing odors and freshening garments.
Iron your shirt on the "Steam" setting after adding one or two spoonfuls of white vinegar to the water reservoir. As you iron the shirt and release steam, the diluted vinegar will deodorize any remaining smell.