In learning to segment sentences into words, I like to use pennies, coins, or some other placeholder for each word in the sentence. I'll dictate a sentence to a child, have the child repeat it, and then say each word individually, laying down a cube for each word. For example, "The man hit the ball far" has six words. As the child would say each word THE - lay down a cube - MAN - lay down a second cube, etc., the cubes would be laid down in left to right order, keeping with the directionality of writing and reading.
It's best to start with shorter sentences like "Be safe" and "Tom is tall" to provide success for the child and gradually build up to longer sentences.
When separating words into syllables, you can use cubes or pennies again, and go through the same process as with sentences. Start with compound words. It's easier for children to hear the distinct syllables in a compound word. For example:
From there you can move into easily distinguishable syllables like:
After that you can go into separating words into sounds. Start with words that only have two sounds.
From there we typically move into words with three distinguishable sounds (shut, map, kite, etc.) and then move into four letter words with easily distinguishable consonant blends (past, stop, stuck, bench, self, etc.
Some games I like to play with the children in my classroom are:
Which word has more sounds, go or elephant? It's easy to distinguish at this point. We gradually make the words of more equal length and see if they can tell the difference.
Which word is longer: butterfly or hat? Again, gradually make the two words of more equal length until you get to words like gasp or grasp and see if they can tell which word is longer. It's challenging, but they love it.