Here's the thing nobody tells you when you start writing product descriptions: the words you'd naturally use are often not the words your customers search. You call it a "tote bag." Half your traffic is searching "canvas bag." You call it "skincare routine." They're searching "morning skincare." Small gap, big difference in who finds you.
Most SEO advice tells you to "do keyword research" and leaves it there. Fine advice, no instructions. So here's the actual method, built around a tool you already have access to and probably never opened: Google Trends.
What Google Trends actually shows you
Google Trends is free and sits at trends.google.com. Type in a search term and it shows you interest over time, on a scale of 0 to 100, relative to the term's own peak. It's not search volume in raw numbers, it's a shape. But that shape tells you three things worth money:
Whether interest in a term is rising, flat, or dying. Whether it's seasonal, and when it peaks. And which of two or three competing terms people actually prefer.
That third one is the one most store owners skip, and it's the most useful.
Compare terms before you commit to one
Open Trends, click "Compare," and add two or three ways of describing the same product. Say you sell reusable water bottles. Try "reusable water bottle" against "insulated water bottle" and "stainless steel water bottle." You'll get a graph with three lines. Whichever sits highest is the phrase more people are typing into Google right now.
Do this before you write your product title, not after. It takes two minutes and it changes what H1 you use, what your meta title says, and what words show up in your first paragraph.
Catch seasonality before it catches you
Search "swimwear" in Trends and set the range to the last five years. You'll see the same wave every year, flat through winter, climbing in spring, peaking early summer. Nothing surprising about that on its own. What's useful is the lead time: interest starts climbing 6 to 8 weeks before the peak, not the week of.
That's your cue. If you sell something seasonal, write the blog post, update the product copy, and get the page indexed before the wave starts, not during it. Google needs time to crawl and rank a page. Publish at the peak and you've missed most of the season by the time you show up in results.
Same logic applies to gift-adjacent products around November, fitness gear in January, back-to-school stuff in August. Trends shows you exactly when last year's curve started moving.
Use "Related queries" to find the longtail
Below the graph, Trends has a "Related queries" section with two tabs: Top and Rising. Top shows what's consistently searched alongside your term. Rising shows what's newly picking up, sometimes a specific product variant, a brand comparison, or a "best X for Y" pattern you didn't think of.
This is where you find your blog topics and your longtail product pages. If you sell coffee gear and "Rising" shows "pour over vs french press," that's a blog post. If it shows "cold brew coffee maker for one," that's a product page you don't have yet.
Filter by country and category
Two settings people skip: the region dropdown and the category filter. If you ship to Nigeria, set the country to Nigeria before you trust any of the numbers, global trends and local trends diverge more than you'd expect. And if your term is ambiguous (searching "jaguar" without a category mixes the car with the animal), narrow it to your industry category so the graph reflects your actual market.
Trends tells you what to search for, not the full picture
Trends is a discovery tool. It won't give you exact monthly search volume or tell you how hard a term is to rank for. For that, pair it with Google Search Console, which is free and shows you the actual queries already bringing people to your site, including ones you didn't target on purpose. That combination, Trends for discovery and direction, Search Console for what's already working, covers most of what a paid keyword tool charges you monthly for.
Once you've got your terms, the rest of SEO is mechanical: get them into your titles, headers, and image alt text naturally, keep your site structure clean so Google can crawl it, make sure pages load fast, and build a few genuine backlinks over time. None of that matters much if you're optimizing for the wrong words to begin with. Trends is how you make sure you're not.