SEO is basically divided into two parts -
On page SEO
Off Page SEO
In On-Page SEO below mentioned elements are optimized -
Meta Tags like Meta title & Meta Description
URL optimization
Header tag
Image Optimization.
Content Optimization
Need to ensure if breadcrumbs are present, images are not bulky, content is fresh, unique & relevant. Technical specifications are added in the content(If Any). Important keywords are internally linked with inner pages etc. Need to ensure web page is user-friendly and can be understood easily by the user.
In Off Page SEO below mentioned Activities are performed -
Social Bookmarking
Social Seeding
Article Submission
Blog Submission
Yahoo/Quora Question Ans activities
Directory Submission
Classified Posting
Company profile posting
Guest Blogging
Forum Submission
Info-graphic Submission
Document Sharing
Need to ensure that off page activities are done on qualitative sites because main aim to perform off page activities is to create backlinks. So these backlinks should be qualitative.
Once these Off-page activities are done then at the end of the month need to perform backlink analysis with the help of GWT or other tools like SEMrush or Moz, ahref etc. and need to disavow the toxic links
source: https://www.quora.com/What-are-the-basics-of-SEO