In my field, some people do systematic literature reviews while others do more narrative-type reviews, where the focus is more on giving a sort of guided tour of the major works and themes. I'm doing the latter type, but if yours is going to be a systematic review, I would recommend looking for published papers with that type of review, to see the sort of detail they give - in my topic there are quite a few of these reviews published, and they tend to set out things like which databases and keywords were used, how they sorted through the abstracts looking for appropriate papers, how many papers they started and ended up with, and so on.