Assess the child's particular difficulty. There are many variations in children's articulation difficulties. Some children say "wunning," instead of "running." Other children lisp, sounding "th" instead of "s". Use repetition to help the child improve pronunciation of sound. Teach the child nursery rhymes and songs to help him relax and enjoy speaking, singing and making sounds.
Use cards and games. If a child cannot say "l" for instance --- saying "back," instead of "black' --- write a list of words, such as "blink," "blind" and "blank." Let the children choose a card and say the word. Praise the child if he gets it right, but do not reprimand him if he makes mistake. Target a few key words and sounds, gradually increasing the number as the child's ability improves.
Ask the child to draw a picture that incorporates some of the words he struggles to pronounce. Help him to name the items on the picture. Ask him to write labels using the appropriate words. As he articulates the name of the item, let him pin the label of the word on the picture.
Help the children to make basic hand puppets. Name the puppets and write a simple script so that the children can present a puppet show. This helps the child to relax and articulate through another "character."