So: how to proceed? On the one hand, SEO best practices recommend that you include relevant keywords in a number of high-attention areas on your site, everywhere from the titles and body text of your pages to your URLs to your meta tags to your image file names. On the other hand, successfully optimized websites tend to have thousands or even millions of keywords. You can't very well craft a single, unique page for every one of your keywords; at the same time, you can't try to cram everything onto a handful of pages with keyword stuffing and expect to rank for every individual keyword. It just doesn't work that way.
QUOTE: “So sites that don’t have much content “above-the-fold” can be affected by this change. If you click on a website and the part of the website you see first either doesn’t have a lot of visible content above-the-fold or dedicates a large fraction of the site’s initial screen real estate to ads, that’s not a very good user experience.” Google 2012
The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.