Read and understand the paper's guidelines. Without understanding the guidelines, you have no standard by which to critique the paper. Carefully look over the requirements. Note if the research is focused on one aspect of marketing or on marketing as a whole. If you have questions about the guidelines or the marketing topic that the paper focuses on, contact your professor before beginning your critique.
Give the paper your full attention, and read it carefully. To critique a marketing research paper, you must make an effort to understand what the author is trying to convey. It's easy to get distracted, which leads to missing key information that you need to understand in order to critique the paper. If you have trouble focusing, split the paper up into sections and take breaks in between.
Take notes. Note things such as the structure of the paper, how you feel the paper contributes to the body of knowledge and how clearly the message is conveyed. Check if the points made in the paper are supported by the sources that the author cited. While it may take some extra time to sift through the sources and make sure that the ideas in the paper are supported, it's essential for writing an insightful critique. Also note the author's grammar and the flow of the paper in your notes.
Ask questions. Marketing is an umbrella over various other fields, including advertising, public relations and branding, and all of these fields are constantly changing. You may have a different specialization than the author of the paper. With that in mind, it's better for you to ask if you're unsure about something, rather than assume that the author is wrong.
Be constructive. When you begin your critique don't just tell the author what he did wrong, tell him what he did right. Include the contributions of the paper along with the limitations. Every research has limitations; that is why market research is ongoing. Keep this in mind and suggest how the research could be improved, rather than just stating that it could be better.