If you encounter anyone who claims to be an “SEO Expert” or “SEO Consultant” or “Search Engine Expert”, etc., and you ask them:
“What’s the most important thing to be careful of when building a web site so that the search engines find it and rank it higher?”
Their answer had better be similar to this:
“It depends” or “There are multiple aspects to consider and the weight of each varies in importance by what your site is trying to convey and what your ultimate goals are…” or “How would I know? Only Google knows that for sure.”
…or they’re completely full of shit.