If Google finds two identical pieces of content, whether on your own site, or on another you’re not even aware of, it will only index one of those pages. You should be aware of scraper sites, stealing your content automatically and republishing as your own. Here’s Graham Charlton’s thorough investigation on what to if your content ends up working better for somebody else.
It's important to check that you have a mix of head terms and long-tail terms because it'll give you a keyword strategy that's well balanced with long-term goals and short-term wins. That's because head terms are generally searched more frequently, making them often (not always, but often) much more competitive and harder to rank for than long-tail terms. Think about it: Without even looking up search volume or difficulty, which of the following terms do you think would be harder to rank for?
QUOTE: “Shopping or financial transaction pages: webpages which allow users to make purchases, transfer money, pay bills, etc. online (such as online stores and online banking pages)…..We have very high Page Quality rating standards for YMYL pages because low-quality YMYL pages could potentially negatively impact users’ happiness, health, or wealth.“
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.
Baseline ranking assessment. You need to understand where you are now in order to accurately assess your future rankings. Keep a simple Excel sheet to start the process. Check weekly to begin. As you get more comfortable, check every 30 to 45 days. You should see improvements in website traffic, a key indicator of progress for your keywords. Some optimizers will say that rankings are dead. Yes, traffic and conversions are more important, but we use rankings as an indicator.