First of all, the "best" way to get ranking is produce quality in-demand content that people want. Then interact with your intended audience, provide them value, and they'll flock in droves to your site.
For the purposes of my answer to the rest of your question I'll define my terms:
"Blog" and "site" and "Wordpress" site are exactly the same thing. They are a container of sorts that organizes and presents a collection of pages and/or posts.
I understand that some people still call an individual post among others, that shows up at one individual URL within some given blogging software installation, a "blog," but I am accustomed to calling one Wordpress installation aka "web site" a "blog."
exampleblog.com is a site/blog/Wordpress installation
exampleblog.com/post-about-green-bananas/ is a post
exampleblog.com/about/ is a page. Maybe. Or maybe its a post. Your choice.
In Wordpress posts and pages are semantically two different things. Your privacy statement, contact form, and About page might be on a page, but your weekly articles or whatever would generally be posts.
If you are going to have a collection of topically interrelated pages and/or posts those belong in one Wordpress installation aka blog aka site.
If you want to keep the world updated on your ongoing search of green unicorns and also write daily reviews of hot chocolate, you probably need two separate sites/blogs/wordpress installations.
Hope that clears things up.