If a child is struggling to pronounce a word, should we tell them to "Sound it Out"? Hmmm. If they knew how to sound it out, then they would not be struggling. The whole reason they cannot "sound it out" is because they do not know the sound.
It is like telling someone, "Go to the grocery store for me". What would you expect them to bring back? Even if you asked, "Go to the grocery store for cookies." Would you still get the cookies you intended? No.
When asking students to read, we need to be specific. If they do not know a sound, then they need to be taught that sound explicitly and repetitively. One way to work with a student at home is to have tiles like Scrabble, shade the vowels and let the student manipulate the sounds around to make real and non-real words. They will see that an "l" sounds like /l/ no matter where you put it in a word. That can be fun to see how silly you can be.
For harder "rules," the student needs to learn specifics. Why does r-a-c-e say "race"? Well, "r" says /r/ but the rest can be confusing. The "a" says its name because the "e" reaches over the "c" and bops him on the head. Bop me on the head and I will never forget. But then the "c" sounds like /s/. That is because it is followed, not preceded, by an "e". So they have to go allll the way over and see the "e" before they know what the "a" says and what the "c" says. And then the "e" does not say anything at all! But yet it has worked very hard to make the "a" say its name and the "c" switch to an s sound.
So next time you ask your child to sound out a word, think about what it takes to do that! If they can't, then they are missing an understanding that needs to be taught explicitly.