Google has more than 500 major and minor ranking factors to be considered while showing results.
But some of the major factors are :
1) Proper title Tag
2) Right Description of the page (Not really necessary because these days google is able to create description for your website)
3) Proper H1, h2 and h3 tags on pages
4) Quality Unique Content (You can never get high rank for a page without content)
5) Number of quality backlinks for your website (Most decisive factor)