It is important plan your strategy early when developing your website.
Your keywords need to be in a hierarchy that includes:
Your homepage – top level – keywords are the most important. They are your primary 5 – 10 keywords from which you build your website.
The aim is at the primary keyword from you top level will generate a collection of more precise keyword phases. Section level are more detailed and targeted. Often these will generate more traffic than all the other pages.
Individual pages have the most relevance and precise targeting and eventually may cover thousands of keywords.