First of all, you have to be an expert on the subject and aware of the recent literature on the topic you want to review.
Define the problem
Re-search the Literature and key results
Take Notes While Reading and description of the current state of the research
Choose the Type of Review You Wish to Write
Keep the Review Focused, but Make It of Broad Interest
Be Critical and Consistent
Find a Logical Structure
a description of potential approaches for the future and perceived challenges
A review article is nothing but a literature review. Unlike an original research article, a review article is a survey and evaluation of already published artcile. It is the most intricate thing while writing a dissertation. When it comes to the number of articles to be included, it depends on the subject or the topic of the article and your knowledge of the respective topics. On a rough gauge, it can anywhere fall between approximately 5 - 20 published papers.
If you want to know more about literature review; you can refer to this blog which explains everything about literature review:
A-Z of literature review - https://typeset.io/resources/the-ultimate-guide-to-writing-a-good-literature-review/