In the same vein, you might draw food drive posters as Melinda did. These not be very skilled drawings, as you say your drawing talents are limited, since the Marthas laugh at her efforts and insult the posters as being ridiculous.

Given that a key section of the book concerns Melinda's attempt to draw a tree, I would suggest you drawing either a tree in the way that Melinda tries to or draw Melinda trying to draw a tree. This will help you to explore the way in which Melinda relates to the tree and the way that it is, to a certain extent, a symbol for Melinda herself.

One of my favorite scenes in the book is Melinda working in the yard. It is where she is cleaning out all of the old and dead branches and weeds. This was a turning point for both Melinda and the story itself.

Another idea would be the scene with Melinda working in the art room; the one where she constructs the barbie, bone, and plastic work.

When drawing from a book, it's best to choose a scene that is well-described. You will want to choose a scene that resonates with you. In other words, pick a scene that you are interested in. If you have trouble drawing, you may want to choose something simple without detailed facial features.