There is a difference between SEO research for ecommerce sites and SEO research for other sites. Amazon is probably a competitor for your own branded ecommerce site. But amazon spends a lot of money to perfect its product and category for maximum online sales. So it is a best place for keyword research. While Google and Amazon both are search engine. The user who visits Amazon its clear that one wanna purchase something. But its not same for Google. 

To find keywords with Amazon, take a look at the list of products you sell. Start typing a word or set of words that describe your product. Amazon provides a number of suggestions through its autofill feature. The feature suggests these searches based on the users queries over time. Lets say you sell beauty products. When you will type on Amazon for beauty products, then it will suggest following searches:

You can see these searches are very specific. You can experiment with combinations of different keywords for the same products. List all the search terms suggested by Amazon on spreadsheet. You need to write only those that are relevant for your business. 

How To Use Your Competitors For SEO Keyword Research?

There are good chances that your competitors have effective SEO ideas, if they are ranking high. First you have to find your competitors. There are so many tools for competitor research. First one is SEMRush. It will show you the keywords your competition  already ranks for. When you enter a competitor’s domain into the search field, and click on organic research, then this tool will give you a full report. The report includes organic search positions that business holds, the keywords they rank for, the percentage of traffic they get for those keywords, and many more things. 

The other tools that you can use for competitor research are ahrefs and Alexa’s Competitors REsearch Matrix.  Each tool works differently. You can choose the tool according to your convenience. 

Now the point is, it’s not all about to just research the competitors and follow their SEO strategies. Maybe they are not engaged in SEO guidelines and in this case if you follow them then you might end up optimizing for lousy keywords. So the next important step is to find out the domain authority(DA) and page authority(PA) of your competitors. Moz is the best tool for this information. It provides a free browser extension called MozBar that you can install on chrome. It gives you both PA and DA for your competitor’s website. 

If your competitors are ranking for the keywords that you want to rank for and they have lower DAs and PAs than yours, take on their keywords and outperform them. On the other hand if your competitors have higher DAs and PAs and they are targeting the keywords that you want to rank for, in this case your best practice should be to identify the keyword gaps and unique variations of that keyword. 

What Resources Are Available For SEO Keyword Research?

For your ecommerce store Amazon and your competitors are the only places for keyword research. Other tools that can also help you in this case are:

• Google: Although Amazon is the best place to know about buyers intent, still Google is the biggest search engine out there. Google’s auto suggest is a quick way to find the suggestions on the real search activity. You can also check the bottom of SERP to get the related search suggestions. 
• Wikipedia: As we all know Wikipedia is a brilliantly-organized and interlinked knowledge base that like Amazon organizes its information by keywords and categories. If a product category you sell has a page, scan the entry for words and phrases. Pay attentions to the topics or keywords you might write blog posts about: 

• Ubersuggest: With the help of ubersuggest you can search either by keyword or by domain. The benefit of searching by domain is you will learn what keywords that site rank for. If you search by keyword, you will get data about search volume, difficulty, and cost per click, as well as related search terms. For instance we can use ubersuggest as below: 

You can click on suggestions for ideas on keywords. 

Google Keyword Planner: There’s an enormous amount of data inside Google Ads, including what keywords businesses are targeting and what they’re willing to pay for those keywords. Google Keyword Planner will generate baseline keyword data, such as search frequency, monthly volume, competition, and variations of root keywords.