Title and abbreviated title
Titles are used by search engines, so it's important to pick relevant words so that others find your work. In general, your title should include your study design, sample population, and what you were measuring. Most journals also ask for an abbreviated title (sometimes called running head) which typically has fewer than 50 characters. It's useful to put this running head as a header on all pages of your manuscript.
You should give the full names of all authors. Most journals also ask for their highest degrees and current place of work. A good idea is to include everyone's ORCID, which means they won't get confused with other researchers that have the same name. You should specify one of the authors as a corresponding author, and provide their email address.
You should provide a few keywords that sum up your work. These are useful when identifying potential reviewers, and can later be used by search engines. Medical research should get their keywords from the MeSH thesaurus.
You should give a word count. Generally you don't need to include the references when counting words. It's also useful to specify how many tables and figures should be present so that reviewers can make sure they see everything.
You should have a section titled "Funding Statement" where you explain who funded the research. You should include all of your grant numbers.
CONFLICTS OF INTERESTS
Your manuscript should include a "Conflicts of Interests" section where you declare any financial or personal relationship that might bias or be seen to bias your work. State whether sponsors had any specific role in the production of the paper. If there are no conflicts of interest, write: "The authors report no conflicts of interest and have no proprietary interest in any of the materials mentioned in this article.".
Your "Acknowledgements" section should credit contributors who did not meet the criteria for authorship.