The goal here was to find keyword variations and longtail keywords for certain main keywords.
To find as many variations as possible, I started out with brainstorming and used a range of free and pro Keyword tools, e.g. Ubersuggest, SEMRush, ahrefs, Answer the Public, etc.
As with any keyword research, it is important to find not only keywords based on search volume/competition but also in terms of relevance and search intent
