Forks are the easiest utensil for children to learn to use, because they don't have to learn to balance or slice anything to use one. Children can learn to "stab" foods with their forks and put the food into their mouths.
Cut the child's food into bite-sized pieces so she can pick up the foods with a fork without assistance. Place the fork to the side of the child's plate; the left side is traditional, but the right side is also appropriate, especially for right-handed preschoolers.
Spoons require a little more technical skill than knives, depending on the type of foods to be eaten. Eating mashed potatoes with a spoon is easier, for instance, than eating peas with a spoon. Teach your preschooler to grip the spoon properly in his dominant hand, and use it as a scoop to carry the food to his mouth. Show him how to lean over the plate to keep spills to a minimum. Place the spoon to the right of the child's bowl or plate for easy access.
Some might say that a knife should not be included in a preschooler's eating utensils; however, a simple child-safe knife, such as one from a child's utensil set, is appropriate for children at this age along with adult supervision. Show her how to make a sawing motion to slice soft foods to start, such as cutting up bananas for a fruit salad or slicing through scrambled eggs. Show her how she can hold the fork in her left hand and the knife in her right as she cuts, or use the knife to push food onto her fork. Position the knife to the right of the child's plate, next to the spoon. You may also consider taking away the knife after she has used it for cutting, to avoid any mishaps or inappropriate play.