Best way is to keep your site fast, give users content they would want to stick to and read or watch. Keep them engaged with suggestions like "Article you might want to read, or videos you might want to watch." Keep the number of ads on a page to minimum and that too shouldn't be intrusive with the UI/UX.
Google doesn't like link building for a site. Any sort of scheme that helps your site gain a backlink is disregarded. The only legit way is to acquire it naturally or at least make it appear natural. Social Media is great place to start with. You can go for niche edits but that's more time consuming and rewards are not always good. Guest posting is decent, but most of the site these day have their metrics up using illegitimate techniques and backlinks so chances are your efforts might go to waste. Blog commenting is mostly useles, you don't gain any advantage and by taking sponsored posts you'