Hi Billy,
The best way is to create a landing page for each location that you want to rank including the keyword in the URL and content. Because the URL is different, meta tags, and part of the content is not considered duplicate content, many nationwide companies use these techniques.
Examples:
Both are acceptable
www.website.com/sg/yishun/seo-service
www.website.com/singapore-yishun-seo-service
XYZ offers SEO service in Yishun, SG
XYZ offers SEO service in Yishun Singapore
Make sure to replace part of the content with the keywords and location for every landing page.
This could be a copy of the home page or service with the above information.
Here is the best example of a nationwide communication company in the US targeting all states and cities.
Florida: https://locations.xfinity.com/fl/
Washington: https://locations.xfinity.com/wa/
Hope this helps.
