Keyword research is valuable because it’s a way to learn how your users search for information. Keyword research can also give you a better understanding of the subject your website will be about.
When doing keyword research there are a few basic ideas to understand:

• Singular vs. Plural—Search engines and keyword research tools handle singular and plural terms differently.
  Apple will return different search results than Apples. Understand how your research tool displays and reports singular and plural terms.
• Word Order and Prominence—The order of the words that are typed into a search box matters, as does the order of the words on a page.
  Macaroni and cheese has slightly different results than cheese and macaroni.
  Some keyword tools will always list words in alphabetical order, something you should be aware of when doing your research.
• Head Keywords—Head keywords are usually short one or two word concepts that can have a wide range of meanings. They have a high volume of searches, but the variety of possible meanings makes it difficult to know what the user was actually searching for.
  An example of head keyword would be golf. Was the searcher looking for shoes, clubs or places to play golf?
• Long Tail Keywords—These are multiple keywords (at least four or five words). These keywords are very specific and signal a clear intent on the users part.
  An example of tail keyword would be Mens black Nike golf shoes.
• There is a wide range of keywords falling between the head and tail.

When doing keyword research it’s important to:

• Compile a list of all of your keywords.
• Try to develop clusters around a particular topic or subject.
  These will become the high level directories in your website architecture.