I like the 70/30 rule (7 out of 3). For every 7 words the KNOW, give them 3 words they are struggling with. If they don't know 7 words yet (and that is perfectly fine) give them 2 they know and 1 they don't. Once they have mastered that word give them the 3 they know and and 1 more. Then add 2 more, etc. They need to feel confident and see progress to want to learn more.
If your child is struggling with she - tell them to remember that sh is Mrs. Elkins favorite diagraph because it says shhhhhh😊
Remember these are sight words. In order for them to be able to move to the next list they have to know the words by sight (under 3 seconds) and read them fluently in phrases (example - she said to)
I hope these tips help!