I had someone contact me about all of the auditory games I play with phonological awareness. The question was how do I know where to work with a child, do I start at the beginning and move through sequentially, and how long do I work on one particular skill. Once you start working with your child, or the children in your classroom, you'll know.
I had a child in tutoring who consistently when spelling would leave out the n's and m's in blends at the end of words like rent and bump. She would spell them "ret" and "bup" because she couldn't hear them. Once I realized why she was spelling them that way, we would spend about 5 minutes at the beginning of our lesson making words with a Montessori material called The Movable Alphabet. I would dictate a word like wet, she'd write it with the letters. Then I'd say, "Now we're going to make it say went." She realized what she needed to do.
She and I worked on this skill at the beginning of our lessons for about two months, then she finally got it. She is a child struggling with dyslexia so we needed to work on it until she'd over learned it, but through working with her I realized where she needed to start with phonological awareness. As you work with your children you will too.
With the 3 year olds in my classroom, we always always always start at the beginning and play "I Spy" with objects and beginning sounds.
If you're not sure where to start, feel free to contact me. :)