At the beginning of the spectrum, you have a child who is stimulable for the target sound, but is having difficulty at the CV, VC, or CVC single-syllable word level. At the end of the spectrum, you have a child who is ready to work on carryover to conversational speech with the sound. Let's look at the steps you can take with the same set of stimuli to vary difficulty to meet the child's needs.
I attempted to get this information down in paragraph form, but it was too wordy. An illustrated flowchart seemed to work better, so here it is. You might consider printing this and attaching it to a copy of one or two of my free articulation card sets and sending it home as homework for the summer with students.