Letter knowledge is the ability to recognize the different letters and their associated sounds. Research has shown that you should start by teaching children upper OR lowercase, but not both to start with. So far, there is no known benefit to teaching lowercase verse uppercase and vice versa.
Books are for infants too! High contrast books with simple shapes help caregivers talk with their babies. Babies also enjoy looking at faces. Here's a list of recommended baby books.
Helping children understand basic math concepts helps them develop positive associations towards math learning and deepens their understanding of math. Pointing out and talking about numbers, shapes, patterns, measurements, sorting, and spatial relationships are all great ways to increase math literacy. - NAEYC
"Graphic novels can be a way in for students who are difficult to reach through traditional texts... Graphic novels can dramatically help improve reading development for students struggling with language acquisition, including special-needs students, as the illustrations provide contextual clues to the meaning of the written narrative. They can provide autistic students with clues to emotional context that they might miss when reading traditional text. English-language learners will be more motivated by graphic novels, and will more readily acquire new vocabulary and increase English proficiency." -Scholastic Inc
Predictable books allow for use of the cloze technique, where words are left out of the story and children are required to fill them in. This is used to increase comprehension. Unconstrained skills like vocabulary and comprehension are the biggest long term indicators of reading success. -Susan B. Neuman
Books without words encourages caregivers to talk with their children; an early literacy skill. Picture walks are also a great way to build reading comprehension.