Introduce one number at a time and reinforce it before you proceed to the next number. Say the name of the number and hold up pictures of that number of objects. To inject humor, hold up a picture with the wrong number of objects, count the objects and reject that picture in mock horror. Help the children write the number of the day in several ways: on paper, in a sandbox, with strips of clay, even in butterscotch pudding.
Use traditional ditties such as "One, Two, Buckle My Shoe" and "The Ants Go Marching One by One," or learn new ones from websites including SongsForTeaching.com. If you're not much of a singer, use CDs to help you out.
Cooking and eating are popular activities with preschoolers, so use them to reinforce learning about numbers. When you make a recipe, have the children read and measure the correct number of teaspoons, tablespoons or cups for each ingredient. When you're serving a dish, count the number of scoops that go onto each plate. As the children set the table, let them count the people who will be eating and lay out the correct number of place settings.
Playing games is one of the most engaging ways to practice using numbers. Nearly every board game involves counting---think Candy Land or Chutes and Ladders. Visit websites such as Education.com to find online math games and other math activities.
Counting and number books provide delightful illustrations to help kids learn. Pick up Dan Andreasen's "The Baker's Dozen: A Counting Book" (Henry Holt, 2007); David Kirk's "Miss Spider's Tea Party: The Counting Book" (Scholastic, 1997), or the classic "Anno's Counting Book" by Mitsumasa Anno (HarperCollins, 1986).