Focus on individual phonemes . Children need to get a feel for each phoneme they will use in reading and spelling. Just as we do not expect children to learn to recognize all the letters at once, neither should we expect children to learn all the phonemes at once. Instead, we spend time with each phoneme they will need to read and spell words. We need vowels right away, because we can't put together any word without a vowel.
Long vowels are easier to identify than short vowels.
Children do not need to be taught every phoneme. As they get used to identifying a limited set of phonemes, they will learn how to identify others. Introduce each phoneme one at a time, setting aside from a day to a week for each one. A good introductory strategy is to use meaningful names. You can also use a stretchable action figure to give children practice in stretching the sounds.