Listen to the teacher when she announces the test. Find out what kind of test you will have and what units it will cover.
Study the material you learned in class. Study the information in the textbook and supplementary materials. Teachers know that a good test should assess what they teach. Look in the textbook for extra practice at the end of the chapter. Look also for extra work in the back of the book. Teachers often take test questions from these places.
Study grammar by learning examples as well as rules. Of course, you should understand the rules. But learn the examples in the book by heart and use them as models. Write sentences of your own similar to the examples. When you take the test, you will remember these sentences. They will help you answer grammar questions correctly.
Study vocabulary in complete sentences. Write the word on one side of an index card and write the meaning plus a sentence on the back. Try to memorize these sentences. Teachers will test to see if you understand the word in a sentence.
Prepare for a reading test by practicing the readings in your book and learning all the new vocabulary. Make sure you also understand the new grammar. Practice finding the main idea, telling what words mean and listing the details. Then practice extra reading at your level without a dictionary. Read each story two or three times.
Prepare for a writing test by writing practice paragraphs or essays. Make up your own topics or take them from the textbook. The end of each chapter in a writing text usually has extra essay topics.
Prepare for a listening test by practicing with the audio materials for the course. If you have a CD or software at home, make sure you understand all the phrases you hear. If not, practice in the language lab. If you have dialogs in the textbook, practice them with a partner until you understand all the sentences.
Study for a speaking test by reviewing the questions or conversations you did in class. Usually speaking tests have a short interview or role-playing. Practice answering the questions you studied. For example, be ready to say where you are from, where you live and how old you are. Or you may have to take part in a dialog or phone conversation. Practice the dialogs in the book with a partner. Then practice doing them with your own words.
Finally, study every day in your ESL class. The best way to learn is little by little as you get new material. Don't wait until the last minute to study for a test. If you study properly, you can do well on your ESL test.