How we write SEO optimized Blog Post

Hi
I want to know "How we write SEO optimized Blog Post?"
I share some points I already Know If I missed something Kindly Guide me.

--Keyword must be in title
--Keyword must be in post Url
--Keyword must be in First Paragraph
--Keyword density is 2-4%
--Keyword must bi H1, H2 tags etc
--keyword must be bold and italic
--Keyword must be hyperlinked to external pages
--Blog post is internally linked with other web pages
--Blog post length is approximately 2400+ words.
--Use keywords in ALT images

I want to know about this
-- How must internal and extenal links per blog post are valuable?
--Can we use 3-4 keywords per Blog post??

Kindly guide me How we Write effective and seo optimized Blog Post smile emoticon

Thanks:)