LSI is a mathematical technique that google algorithm has incorporated to display search results by identifying the patterns in the relationship between terms and concepts with respect to the search queries made.
The approach of Google for LSI algorithm is to avoid repetition of same keywords all the way through the content yet having a relevant content under the given search queries. So using LSI keywords, it adds variation to your content and still get a score on those keywords for ranking without any risk of keyword stuffing penalty.
For example, if your main search keyword was “seo education,” the target should not be on single keywords like seo, education or seo education in relevant content. You should use LSI keywords such as “seo marketing education”, “learn search engine optimization”best seo education”, “seo training” ,”google free seo tools”, “learn seo free”, “seo for higher education”, “search engine education”, “seo learning”, “seo college” etc
There are different methodologies how you can identify and implement LSI keywords. Search results are one of the best sources to find LSI queries. When you try to find something on google, with entering your keywords in google search box, it will automatically display a number of semantic search terms at the bottom of your search engine results page.
Another practice could be identifying from a google keyword planner tool that suggests the numbers of these semantic keyword options.
Apart from google sources, there are numbers of the free third party online LSI generator tools like LSIgraph.com from where you can undertake and implement these LSI terms to your website for optimization, content development, and link building.
Whatever the methodologies and practices you integrate to enhance your SEO campaign, the main keywords, and LSI keywords should come into place naturally and the focus should be always on facilitating the users experience with relevant contents that they are looking for.