There are no essays or short-answer portions on the Praxis reading section of the exam. Every question is multiple-choice and asks you about a brief passage, a longer passage, a pair of passages, or a chart or graph. Here are some hints for doing your best:
Always read the whole passage before you look at the question and the answer choices.
When a question asks for the "main idea" or "author's primary purpose," steer clear of overly detailed answers and pick the broadest answer choice that isn't wrong.
The passages are excerpted from writers who know what they're talking about, so no statement that is factually false is ever a correct answer. You don't need outside knowledge to answer the questions correctly, but you can eliminate wrong answers based on outside knowledge when and if you happen to have some.
When you see a set of paired passages (from "author one" and "author two"), take a few moments to develop a sense of what the two authors agree or disagree about in your own words before you look at the question and the answer choices.
If the visual-information questions (the ones about charts and graphs) make you nervous, rest easy in the knowledge that they're near the end of the test, which puts you in a good position to judge how much time you have left and verify your answer by plugging in the wrong answers to double-check that they are indeed wrong.