Here's a good links to read:- 

• SEO Tutorial For Beginners in 2018
• How to Use the SEO Checklist for Drupal
• http://www.weebpal.com/blog/top-drupal-seo-modules
  1. SEO Checklist (MUST HAVE)
  2. Pathauto
  3. Redirect
  4. Global Redirect
  5. Page Title
  6. Metatag
  7. Search 404
  8. Content Optimizer
  9. Drupal SEO Tools
  10. Menu Attributes
  11. Menu Breadcrumb
  12. Links Checker
  13. SEO Compliance Checker
  14. Xml sitemap
  15. Site Verification
  16. Html Purifier
  17. Tag Clouds
  18. Taxonomy Title
  19. Google Analytics
  20. Mollom
  21. Schedule 
  22. Diff
  23. Rdf
  24. Easy breadcromb
  25. Sitemap
  26. W3C Validator