There is one tool that shows you what Google actually does with your website: which pages are in the index, which search terms you appear for, at what position, and where Google fails to read your site. It comes from Google itself, it costs nothing, and a surprising number of small sites have never set it up. Google Search Console.
Analytics tells you what visitors do on your site. Search Console tells you how they get there in the first place, and whether they can. The two answer different questions, and for anything to do with visibility, Search Console is the more important one.
Verifying: the step that stops most people
Before Google shows you the data, you have to prove the domain is yours. There are two ways to do that, and the choice decides how much you see later.
The domain property covers the whole domain, including every subdomain and both protocols. It is the right choice, but it requires you to add a so-called TXT record with your domain provider. That sounds more technical than it is: you copy a string Google gives you into your domain's DNS settings, wait a few minutes, click verify.
The URL prefix property covers exactly one address, say https://your-domain.com. It is quicker to set up because you can also confirm it through a file on the server or through an analytics tag you already have. The catch: if people reach your site with www in front and you only verified the version without it, you miss half the data.
Take the domain property if you can reach the DNS settings. The TXT record is work once and never a concern again.
Submit the sitemap so Google does not have to guess
Once the property is verified, you submit your sitemap. Under Sitemaps you enter sitemap.xml and click submit. Most builders and content systems generate this file automatically; you check whether it exists by opening your-domain.com/sitemap.xml in a browser.
The sitemap does not force Google to index everything at once. It is a map, not an order. But it speeds up the point where new pages get found at all, and that is exactly what matters for a site that is only just building out its content. If you want the reasoning behind why topical breadth matters, it is in finding SEO problems.
The report that sits above all the others
If you could only open one report in Search Console, it would be the page indexing one. It splits your pages into two piles: indexed and not indexed. And for the second pile, it states the reason.
This is where Search Console beats every other SEO tool. A crawler guesses why a page does not rank. Search Console writes it down for you: "Excluded by noindex tag", "Alternate page with proper canonical tag", "Crawled, currently not indexed". Each of those phrases points at a concrete problem you can fix. Anyone who crawls instead is looking for the answer inside their own site while Google already noted it down.
Work through the three most common reasons in the not-indexed pile before you open any other tool. How to sort the findings by impact is in finding SEO problems.
The performance report: where your real chances are
The second indispensable report is called Performance. Here sit the queries you appear for, with impressions, clicks and average position.
The gold seam in it: filter position to the range between 4 and 15 and sort by impressions. Those are pages Google already considers relevant but that sit just below the click zone. They need no benefit of the doubt anymore, only a better answer. Why that particular range is the cheapest lever for more visitors is in increasing website traffic.
Getting a single page checked right away
One tool in Search Console that gets used too rarely: URL inspection, in the search bar at the top. You enter the address of a single page and get its current status within seconds: whether it is indexed, when Google last visited it, and whether there were problems reading it.
The practical use comes when you have published a new page and do not want to wait for Google to find it on its own eventually. After the inspection a button appears, "Request indexing". One click puts the page in the queue, and it is often in within a day or two rather than weeks. Do not overdo it, the quota is limited, but for the two or three important new pages it is exactly the right tool.
A word on patience
A freshly verified account shows little at first. The data fills over days, the index report sometimes takes a week to show a complete picture. That is not a fault and not a reason to check three times a day. Set it up, submit the sitemap, and look again in a week.
Where to start
Create a domain property, set the TXT record with your domain provider, verify. Submit the sitemap. Then wait a week and open the page indexing report. What sits in the not-indexed pile is your first to-do list, and it comes straight from the source that matters.