Basically there are 3 levels of keywords which can be targeted for a website.
:: Local
:: Nationwide
:: Global
Local Keywords: are area / city specific like SEO Agency London, SEO Agency Dallas. These are basically a combination of the keyword and the location. Here SEO is the keyword and London / Dallas are the locations. The competition of these keywords is less compared to National and Global keywords. Local keywords would give you targeted traffic and would have enquiries from people looking for services from vendors located in a specific area. Example: Someone who has a restaurant in Houston would optimize his website for keywords like: Chinese Restaurant Houston, Restaurants in Houston etc as he provides services in Houston and not in any other city.
Nationwide Keywords: These are country specific keywords like SEO Company India. These are used for people looking for SEO services from Indian based companies. The competition for these keywords is Medium Level or if I may say not easy to rank on. National Level keywords are used a lot by Exporters who know that their clients are looking for products or services from a specific country. Search Engines also have country specific versions for searched like: www.google.co.uk, www.google.co.in, in.yahoo.com Example: We offer SEO Packages and we know people are looking for Affordable Packages from India so we have optimized our webpage for keyword: Affordable SEO Packages India Similarly A Travel Agent / Tour Operator offering travel packages to India or UK would optimize his website for keywords like: Travel Packages India, Tour Operator UK etc.
Global Keywords: These keywords are pretty tough to rank on as these are the services without any location attached to them like: SEO Company, SEO Services, Cheap SEO Services. Here you would be competing with companies based across the global. Ranking on Global Keywords might take 3-18 months depending on the competition of the keywords and how aggressively people have promoted themselves on these keywords.
Example: A Software Development Company which serves clients across the globe would be targeting keywords like: Software Development Company, Software Development Services etc
Depending on the products and services and your target market you can find out which keywords you would like to focus on to get a fair share of the leads / traffic generated by search engines.