I would start with a literature search on PubMed. First you will have to define the search parameters, for example 'schizophrenia AND cognitive neuroscience' (https://pubmed.ncbi.nlm.nih.gov/?term=schizophrenia+cognitive+neuroscience). This will give you 3,862 results, which are too many to include in a review, so you will have to narrow down the topic of your review. You can use more search parameters to narrow down the topic but you can also use filters, for example you can select only papers for which the full text is freely available (now you have 1953 articles left). If you then filter for 'human' species and 'English' language, you are left with 1161 articles (both reviews and trials). If you now filter for 'Review' under article type, you will get 265 results. This means there are already 265 articles with a general review of cognition in schizophrenia, and you will have to find a very specific subtopic to make your review stand out. After you are left with 100-200 papers, you can start to extract information systematically from the papers (e.g., in an Excel-sheet). Make sure you list everything you want to extract from the papers before you start reading! Then discuss the search criteria and angle of the review with your supervisor / a colleague before you start reading and extracting information.
Hi Claire, I too am beginning to write more literature review articles and find it much different than original research articles. This following article has been pretty helpful for me Article How to Write a Literature Review Paper?
. The article speaks more in terms of how to write the literature review. As in providing value on the topic rather than simply giving an overview of all the literature you searched. It is fun reading all the findings on a topic that interests you, I hope you enjoy it!