How to promote the internal sections of the site using natural links?

Question

Marketing

Hello seo experts. I would like to know what methods you know about promoting internal sections, for the ad portal and for the online store. Interested in ways to get links.
I will describe two situations.
1. There is a thematic large portal and it has many internal sections with announcements. How to raise these pages to the top with natural links? How to get links to the internal section. What factors do you think have the most impact on ad placement on the top pages?
Explanation:
We know how to get natural links to the main page: partners post, media put reviews, indicating the main one as a source. But the internal pages of the sections do not receive such a trust (((
About what needs to be analyzed, the top issue content listings is obvious and understandable. Technically, the site is close to perfect.
2 Situation.
There is an online store technically perfect. How to promote internal sections to the top for very competitive requests. for example, buy a children's orthopedic mattress
How to get links to this section? what ways? Only buy? . Your opinion is how important links are for promoting the commercial section of an online store, provided that all internal factors and technical condition are close to ideal.
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