There are several factors which you must follow:
On-Page SEO factors like keyword in title, h1, description, anchor text, alt text, duplicate content, outbound links, image optimization, content updates etc.
Site factors includes sitemap, SEO and Mobile friendly websites, domain trust etc.
Off-Page SEO factors: DA and PA of sites, dofollow links, link anchor etc
Domain factors: CTLD extension, Domain title length, Domain age etc.