After every lecture week go back through the material and write eight to 10 multiple-choice questions on topics or sections the class seemed to have trouble understanding. If the students asked a lot of questions about one particular subject that is important to the class curriculum, make sure to have at least two or three questions on that topic on the test. Some schools have a test bank available to teachers; this can contain questions from previous tests given or from outside sources the school has compiled.
At the end of two or three chapters go back through and make a test question bank for the topics the students seemed to understand or topics there weren't a lot of questions for. Some textbooks have a website set up by the publisher, including a test bank teachers can pull questions from. These can be good avenues for finding the right question on a selected topic. For easier topics, the students can be asked to give a brief presentation over a topic and provide a few questions covering the material presented. This can be a great avenue to generate questions while making sure the students understand the material.
Once the multiple-choice questions have been generated, choose questions from every chapter, making sure to include questions from the topics that seemed harder for the students to understand. Label this test template A. In a separate document, mix up the question order and call this test template B. You can do this for as many templates as needed. When the tests are handed out in class, make sure to hand out the different templates with the various question order; this cuts down on cheating while testing students on the same questions. Another approach is to use template A for one class and another template for a later class to discourage outside test talk and cheating. The same technique can be used in using tests for different semesters as well.