It's fun to be the one to teach preschoolers about counting and numbers. A remarkable process takes place when these young children associate a group of three dogs, for example, with the word three and even the number three.
One tool I like to use is no error cards. These cards are created so when young children are learning their numbers and associating objects with words and numbers, they won't make a mistake.

Here's an example of a no error card using cats and dogs.
Each number card has the number at the top. Then it has the same number of pictures as the number on the card.
Children will count as they place a clothespin on each picture on the card.
When they’re finished, a card with a 3 on it and 3 pictures will also have 3 clothespins. As you can see, the students begin to make the association with the numbers, words, and objects and since each picture will have a clothespin on it, there is no way the student will get the wrong "answer."
Another tool I like to use it Clip It Games. This is a follow up to the no error cards. I like these games because they help students learn their numbers and they also work with their fine motor skills.
Each student will take a card and clip a clothespin on the correct answer.
You can find my No Error Cards and Clip It Games in my Cats and Dogs: Math Games and Math Centers Beginning Number Concepts Numbers 1-10 set.