I've been doing SEO consulting for five years. Instead of fancy talk, I'll leave two lists: what works for me and what doesn't. Each point is based on my observations from my own client portfolio, not universal laws.
WHAT WORKS
One. A page that fully answers a single question. A page that finishes one topic, rather than skimming five. This has been the most consistent result-getter.
Two. Updating existing pages. It delivers results faster and cheaper than opening new pages. Content stuck on the second page can jump to the first when updated.
Three. Page speed — but only if you're slow. If you're already fast, speeding up further changes nothing. It's a threshold issue, not linear.
Four. Internal links. The cheapest and most neglected task. Linking from your strong page to your weak page meaningfully is an edit with zero cost.
Five. Content written with real expertise. Texts where the author is known, shares experience, and gives concrete details. The differentiator isn't length, but details no one can copy.
WHAT DOESN'T WORK
One. Keyword density. Sprinkling the same word throughout the text. This was questionable even ten years ago, now it's a complete waste of time.
Two. Bought links. You might see movement in the short term, but in the long term, it's risk and money loss. Recovering is much more expensive than never doing it.
Three. A target of X blog posts per month. Volume targets push you to fill content. Five good pages do more work than fifty mediocre ones.
Four. Doing exactly what the competitor does. The competitor's ranking might come from their ten-year history, not their content. When you copy, you're only copying the visible part.
Five. Guaranteed ranking promises. I can't offer them either, and don't believe anyone who does.