Tina wants to read for understanding. As Tina checks her own reading, she should
occasionally pause to make sure she understands.
read until the end of the book without stopping.
find other books by the same author.
think about different endings for the story.

Occasionally pause to make sure she understands.

Explanation:

It is important that we fully understand the deeper meaning behind every bit of the plot, every single character, the purpose every event has, the significance the author felt it would bring to the story.

If you read until the end of the book without stopping, you don't get to fully experience and enjoy the book, nor will you be able to comprehend as well as someone who took their time, dissecting every scene and bit of the plot.

Although finding other books by the same author can be beneficial, it will not help Tina to understand that particular book that she is reading. Let's say the author wrote a book about psychology, which Tina is now reading. If Tina finds another book by the same author about, say, play-doh, and how good it tastes (ngl, this is a strange one), it wouldn't help to deepen her understanding of psychology and the author's message.

Tina should not think about different endings of the story. Not if she's trying to read for understanding. This action may distract her, and possibly confuse her. This can also take meaning away from the plot itself, and making up different ending scenes where Jack ends up with Rose won't really contribute to her understanding of the book.