Empirical research is based on scientific experimentation or observable evidence. Writing a critique of such a paper requires the reader not only to judge the author's communication abilities but also to assess his research methodology and effectiveness. A good critique addresses all aspects of the paper, from the grammar to the content to the conclusion, and will help the researcher to hone his skills and improve upon his methods in the future.
Review the topic or goal of the paper before you read it. Make sure you clearly understand the problem that was being researched.
Read the paper once through without writing any detailed notes. You may mark where you become confused or develop questions, but do not elaborate on them yet. Some of your questions may be answered later on. It is best to get a clear idea of the whole paper before dissecting it.
Ask yourself a few questions based on your first impressions of the paper. Was the problem clearly defined? Was it addressed with equal clarity? How thorough was the author's research process? Were there any obvious gaps or overlooked variables? Was the research material or sample size adequate in solving the problem?
Examine the author's sources. Check to see whether all citations are properly formatted. Note whether there any claims that are not backed up by source material or empirical data.
Go back and address each of the points you marked in your first read-through. Give each point a clear, detailed analysis. If you found flaws in the argument, articulate these clearly and objectively. Even if you do not agree with the author's conclusions due to your own personal beliefs or biases, your feelings must not enter into your critique. If you feel that the researcher could have improved upon his methods or explanation, explain to him what you would have done differently.