In the package of measures during a search engine optimization there shouldn`t miss out a specific web technical enhancement of the website.
This means to make a website basically readable for the relevant search engines. Only if a website is readable for search engines it can expand into the index of a search engine and can be found with certain keywords and search terms.
A good evidence for this is the XHTML or HTML alidator of the W3C-Consortium with whom a website can be tested on its readability and HTML (Hypertext Markup Language) conformity.
Also the analysis tool WebXACT from Watchfire that additionally scans a website for its accessibility.
And last but not least at HTML Source or HTML.net the interested webmaster finds online-html-tutorials who inform about the possibilities of HTML (e.g. for webdesign) and about HTML tags who should be avoided.
If you need further information about web accessibility you can also visit the "Human Ability and Accessibility Center" from IBM.
Furthermore you should ensure that the website does not contain any broken links. You can check the links of your homepage e.g. with the W3C-Linkchecker.
If you want to know how a search engine reads your website you can simulate it with the seo-tool from Webconfs.com or you just view your website with a text-based browser like Lynx.
If you are looking for PHP-Scripts in Germany also visit the German PHP programming portal of Fabian Schneider.