Organic search for landing page, how to improve it SEO

Question

I have few landing pages, each page contains contains unique article and description about person(same on each LP) - who will do the service explained in article. LP are posted to google by sitemap, and no links to it from website, but LP contains few links to website(part of site menu, at bottom). Goal of LP is to fill form and booking service, meeting with a person. If goal not meet, visitor can go to site, few links available to it, it also fine. Aim of LP to be searchable on some keywords, and do so only with organic search.
Should LP have links from website, will it improve SEO? Can content be similar or equal(partially) as one of website's article, or must be unique?
I have good organic search results for some rare keywords, how to give LP priority on this keywords?

I'm a programmer, not SEO specialist, please help with some ideas.

Site have zero budget on advertising.

I don't known English very well, may be somebody can edit post, to make question more clear.

Answer 1

If you have two (or more) pages with (too) similar content, you should somehow "tell" Google that it's just copies, choosing one page as "the one". Moz article on duplicate content.

So tagging the LP versions as canonical could further improve their ranking.

As for the links to your landing pages from the website, in terms of rankings they can help if done properly. Also, if you have content on your website, that is accessible to anyone, doing a google search, why not link it from the website as well? I for one would be a bit confused - getting to a landing page, navigating the site, then not being able to find the landing page again from the website, without googling it.