Your first 250-300 words of text on your home page will greatly determine your website’s relevancy to a search engine query, so it should contain your major key words and phrases. (Your headline is also used by the search engines, so use keywords here as well.)
Search engines assume that the most important information about a website’s contents is in the top section of the site’s home page. Since this is also the first area your users will see, it is important that you clearly state what the site is about here.
Ideally, you should have at least two paragraphs that describe your business and the area you work in. It can be similar to your description meta tag, but not exactly the same. Unlike the description meta tag, this text is read by both people and search engines.
Having well written copy here is crucial: not only will the search engines use it, but it will also be your visitor’s introduction to your services. Be concise and honest, and avoid superlative terms like “greatest,” “best,” etc. Like they say: there is no second chance for a first impression.
Spend some time developing your copy; if you have previously written marketing material, say from a brochure or a one-sheet, you may want to use this and edit portions of it to fit your website needs.