After you've compiled a list of key features and ideas, write your review.
Remember to be helpful to the reader, explaining as well as you can every thing. It's important that people find your review useful.
Also, say things as they are, don't tell them to join,buy only because you're using the product. If it has bad parts, tell them and let the people decide. Psychologically, this has the effect of making people think they're in control, and that's true.
Now, SEO it as well as you can:
Important thing about keywords: Include them in your post, but write naturally and don't make them seem forced.
1. Use keywords in the title, in the first paragraph, the last paragraph, and in every alt text of images.
2. Write a meta description containing your keyword and a brief explanation.
3. If possible, make a video, upload it to YouTube and embed it to your review, as it will help your rankings.
4. Give your honest opinion on the product. Keep it conversational and let people trust you.