My daughter's 2nd grade curriculum (K12) focuses a lot on reading comprehension.
First, before each lesson, we used to define the following words: character, plot, setting, theme, etc. until she really got the hang of what they meant.
Second, they do something called a "book walk." I have since quit doing it because after awhile, she got the hang of everything and no longer needed it, but it was helpful. Basically, it's like taking a stroll through a book without reading it...read the title, author, etc, check table of contents, flip through and look at the pictures, make guesses about who the characters are and what might happen, etc.
Then, this curriculum had us stopping after every two pages or so to ask question like, "Who did we meet on this page? Are they a main character?" and "What just happened to So-and-So? What do you think will happen next?"
Having discussions like this while reading really does help with comprehension.