[CAUTION: I am not a teacher:take the advice and or corrections offered in this post at your own risk.
If you doubt the information, please get a qualified opinion from one of the teachers on these forums.]
I'll go one step further and state clearly that my advice may have no effect on your grade whatsoever.
Reading comprehension is so broad, but for test taking, let's think about a few key strategies.
I suggest you:
Read. The fastest way to raise your reading comprehension level is by reading, not for a test, not for school, for your own interest, do it early and often.
Read for main points. This will feel strange at first: read the title and first paragraph of your article, then the first sentence of every paragraph and the last sentence of the entire article very carefully, and before you read anything else.
Read the questions first. Finding information, especially in limited time is much easier if you know what you are looking for. Read question 1, then try to find the answer, then question 2 and so forth.
Learn to scan for words and sentences. Randomly pick a fairly common word like "with". Try to find every "with" in a sample of writing as quickly as you can. This is only for training your eyes.
Pick a word that you believe will only be found in a specific piece of writing, like the word "valve" in a medical article about the heart, and try to find every reference as quickly as possible.
If a question is too hard, mark it, skip it, and go back to it after you finish with the rest. Remember, some teachers cruelly put hard questions first to eat up your time.
Reading comprehension tests often as a general question like: what is the main idea of the article (look at the title). If there is no title, you may even be asked "what is a good title for this article?" be sure to focus on the answer that includes all the main ideas of the article.
If you are asked about the tone of the article (humorous, serious et c.), god help you. Just kidding, but a question like this really demands a fairly good understanding of the language which brings me to my final point, just do your best and remember, its just a test.