Let's dive in:
What is a keyword? We might assume that a keyword is a single word that helps describe what your business does. In fact the best key words are a phrase (often called long tail keywords) that helps begin to narrow down exactly what you offer as a business for example.
If you're a business that offers a product or service is particular location then a long tail keyword for you might look like 'handmade gift shop Staffordshire' or 'handmade gift shop near me' to support those searching while in your location.
If you're offering a specific service then rather than 'counselling services Staffordshire' it might be 'counselling services for children in Staffordshire'
Get the foundations right. As always when starting any kind of marketing analysis, go back and remind your self of your key customer types and personas. Remind yourself of who they are and what they need to help you predict what they need most and might search for.
How to find great keywords for your business? Here are a few steps:
Start with a simple Google search. Google's AI will 'give away' a lot of great info based on what are common searches in your topic area. For example, if you start to type a couple of words, it will start to bring up long tail options that are common or specific. This starts to give you good insight into how users search your type of business.
Connected to this, head to the bottom of a Google search results page and Google will also give you 'related searches' - again free insight into what users are really looking for.
Use a keyword search tool. There are lots out there and some of them are free.
Keywords Everywhere is a Chrome extension that gives you additional data every time you search.
Google Adwords give tons of insights for free - simply set up the account and search (no need to place an ad!)
Semrush is considered a favourite and you can get a free trial.
Moz.com is also popular and offers a free trial.
Find out what people searched for to arrive on your website. Use Google Analytics (check out Acquisition) and Google Search Console (go to Performance then Queries) to find out what folks are actually searching for to arrive to you. There may be a difference in what your keyword search tells you. What does this mean? It might mean that folks land on your website for reasons you hadn't thought of or realised. It might mean that you're not using enough of the keywords you've researched and are therefore attracting users who don't want or need what they find on your site.
How to use keywords. So how can you leverage these keywords to bring in more users to your website and, more importantly, get them to 'convert'? Here are some tips:
Check out the Meta titles, headers and meta descriptions on your website. For examples if you hover your cursor over the header tab of you webpage in your browser (little tab at the very top that shows you what open in your browser) it will tell you what this page is called. If you home page says 'Home' then clearly users will never find it because they're not searching 'home'. However if it says 'Holiday Cottage with Hot Tub, Lake District' then it's much more likely to be found.
Use an SEO tool on your website to get this information easily and add to your website. Wix has its own as does Squarespace. Wordpress uses 'Yoast' plugin which is free.
Don't forget the content inside your site. Just the words are so important. Use the long tail keywords you've identified but is a really natural and 'organic' way so that Google doesn't start to suspect you're 'stuffing' the words in for SEO.
Blogs really help. The advantage of a blog is it allows you to legitimately re use long tail keywords often within different topics and also provide Google with fresh content.
Don't forget images. Google can't read your images so make sure they not only describe what the image is but also sometimes includes keywords. For example having images of your 'Holiday Cottage with Hot Tub in the Lake District' is ideal.
Finally, make this activity a habit. What I suggest is that you regularly check out keywords and trends using Google search and Google Trends. This helps you stay ahead of the game especially if your sector uses a variety of different terms. BUT don't over engineer or 'fiddle about with' your SEO too often. This will confuse Google and reduce its trust in your site. Better to evolve what you're doing on your website by adding more blogs, changing some copy or adding new images then constantly changing header titles.