When you are thinking about developing a website, it is a good idea to perform some market research - in particular competitor research.  There are a number of tools and techniques you can use to identify how competitors of yours have optimised their websites for success.

Understanding which keywords are used on competitor's websites will assist you in developing a website structure and content that will raise your search ranking.  A tool like Keyword Spy provides a free trial account to analyse exactly what your competitors are doing online.

• Ads – what ads your competitors have published online, how much they spend on PPC ads each day, how many clicks they get through these ads, what position their ads typically reside in search engines (e.g. do their ads appear on the first page), what ROI they get, how much they pay per click (Cost Per Click – CPC), what search volume the ads receive.
• Paid Keywords – what major keywords are used and its position in search engines, the CPC, and search volume.
• Organic Keywords – which organic keywords they rank well for, the position in search engines (e.g. 1 = first page and first entry when searching), how many search results there are for that keyword and URL the keyword is ranked for.
• Competitors – who their major competitors are and their keywords (this is great because it gives you an idea of the other websites you should look at).

Another free tool is Google's Keyword Tool which provides a simplified view of keywords on competitor websites - its not as detailed as Keyword Spy but it is also easier to understand if you are just starting out in this area.  Simply type in your competitor's website address to find out the list of keywords that may also suit your website.