Here are some vital components that I ask my students to include in a review article:
*A small amount of summary-enough to let your audience know what the title/author of the work is, along with the basic premise of the plot. That being said, make sure you don't give too much away; part of the function of a review is to encourage or discourage the audience to experience it for themselves.
*Specific attributes. You want to tell us what, specifically, went right. Rather than praising the text as a whole (ex. Brad Pitt had great acting!), give us the reasons for that assessment (ex. Brad Pitt's nuanced expressions offered layers of complexity to the straightforward lines of his character.)
*Specific weaknesses. In the same vein, don't forget to be a little critical as well. Even the most riveting text can usually be faulted for something, and it's the reviewer's job to point that out. Again, this should be specific. Instead of (Stephanie Meyer's writing isn't that good), you could write (Meyer's sappy, overemotional prose leaves little substance for the thoughtful reader, particularly during the love scenes.)
*Comparison. Another thing to mention is how the work stacks up in comparison to other versions with a similar theme or previous installments of a series. Is this work what audiences have come to expect from this author/director/genre/series?
*Numerical rating. How many out of five stars?
*Tone of expertise. Finally, even though a review is clearly a subjective thing, take out any "I think" or "It's my opinion that" statements. You are the reviewer. State your opinion as fact. (Rather than "I think that Monster's Inc. is a fantastic ride for children and adults alike", write "Monster's Inc. is a fantastic ride for children and adults alike."
Just to add to all of these excellent suggestions, one vital stage that I find really hard to get my students to do is the stage that comes at the end of the process: checking and proof reading before submitting. So many of my students just submit their work without checking it, and as a result it contains many glaring errors, inconsistencies or mistakes which a quick review could easily have solved. So don't make the same mistake and get the grade you deserve by quickly reading through it before submitting!
You might also consider, in an article, the validity of the argument the author is making. What rhetorical devices are being employed and how effective are they in the overall article? Too much emotional rhetoric, for instance, would spoil the purpose for some readers; too much logical rhetoric would spoil it for others. A balance of the two appeals would be the best bet for effectively reaching and engaging the most reader membership.
In a movie or theatre/play review, you migh also consider such elements as music, lighting, camera angle, and special effects for overall audience reaction.
Another key point in writing a review is to provide context for readers. Don't assume that your audience is familiar with the work you are reviewing. For instance, if you are reviewing an article or book, establish some basic facts. Who wrote it? Where/when was it published? What does it concern? Summarize briefly its content. If you are reviewing a movie, follow the same line of thinking. If you were reading a review of this movie and had not seen the movie, what information would you need to understand and appreciate the review? Provide for your reader what you would need in that circumstance. Ground the reader in some basic information before beginning to address the work.
It is important to remember that a review is different than a report. In a review, you want to express an opinion or expound on the topics presented rather than simply summarizing (like you would in a report). The first step in writing a review is to read (or watch) the work in question. It might be helpful to take some notes while viewing the material. Jot down anything you liked, disliked, or just wanted to say something about. Actually writing the review article is not that different from writing any other essay.
To write a good review of anything, you need to break that thing done into parts or components and then evaluate how those parts work in relation to the whole. For example, if you were to review of movie, you could consider elements such as plot, acting, camera work, length, music/sound etc. You would perhaps comment on each of these -- pros and cons -- and then relate how all these contribute the overall effect of the movie.
For a product, you could look at its features: cost, durability, user-friendliness, features. You could comment on each of these things -- pros and cons -- and then relate to the overall value of the product.
The first step is to be familiar with what you are reviewing whether it is a movie, a book, or some kind of physical object. Without actually knowing the ins and outs of what it is you are reviewing, the review will likely come off as staid, boring, or just lacking specific information
The second step is to think about your audience and how to appeal to them. Your review will be different if your audience is a group of teens or if it is a group of adults. You have to cater the language and content to your audience.
Another important step is to make sure you know the requirements or limits of the place you are submitting your review to. Make sure you meet minimum word counts, etc.