Before children learn their letters, be sure they can pronounce the sounds of English distinctly. There are 48 sounds of standard American English, although regional dialects might include more or fewer sounds. The 48 single, distinct sounds are listed on the chart below. Say those sounds and then ask your child to repeat those sounds. 
You might wonder, “Is this really necessary?” Yes, it is. Almost always, you will encounter a sound that your child cannot hear or say properly. Let the child listen and repeat the sounds correctly until you are sure the child can hear and say the sounds. You can do this with a child as young as two. Only when the child can hear and say the sounds is it time to associate sounds with letters.
48 distinct sounds in standard American English:
comicphonics for early readers 