I can only suggest, from my own experiences..Always write what you know about. Do not copy and paste from other reviews or from other sites. When and if you do want to use a phrase or quote from somewere else, give credit where credit is due. Dont let people think you wrote it.
If you write a review on a book or movie, PLEASE, read the book or see the movie before writing. Ive read some things on here that seem like the writer read the book jacket or copied a review from a newspaper or magazine. If you write about a certain product, use the product, then write what you think. Dont go by what others write and then guess youll feel the same way.
Dont be argumentative and put other peoples opinions down. They write their opinion and yours could be completly different.(For example: "So and so wrote that X is a wonderful product. So and so must be crazy because I hated it." ) An opinion is your own thoughts on something, not telling us that someone elses opinion is wrong.
Dont try to use words or language you yourself do not understand. When you try to do that you usually wind up using the incorrect wording, and you make yourself look the fool.
Keep your review to the point and dont try to add words as fillers to make your review look longer.
Keep it simple and get to the point and do not make it overly technical. Most people wont understand the inner workings of a lot of products, they just want to know, your opinion of the, service, the reliability, the food, the plot and acting etc., and the overall experience you had.
Take it or leave it, this is MY opinion.
Thanks for reading.