If you decide to use dynamic pages (i.e., the URL contains a '?' character),
be aware that not every search engine spider crawls dynamic pages as well as static pages.
It helps to keep the parameters short and the number of them small.
(See: query strings)
Keep the links on a given page to a reasonable number (fewer than 100).
Maximum size of 100 KBytes per document.
Reasons your site may not be included
Google tells the possible reasons they may not include a website:
Your pages are dynamically generated. We are able to index dynamically generated pages. However, because our web crawler can easily overwhelm and crash sites serving dynamic content, we limit the amount of dynamic pages we index. (See: query strings)
You employ doorway pages. Google does not encourage the use of doorway pages. We want to point users to content pages, not to doorways or splash screens.
Your page uses frames. Google supports frames to the extent that it can. Frames tend to cause problems with search engines, bookmarks, emailing links and so on, because frames don't fit the conceptual model of the web (every page corresponds to a single URL). If a user's query matches the site as a whole, Google returns the frame set. If a user's query matches an individual page on the site, Google returns that page. That individual page is not displayed in a frame -- because there may be no frame set corresponding to that page.
Reasons to an expulsion from the index:
Writing text that can be seen by search engines but not by users.
Setting up pages/links with the sole purpose of fooling search engines.
Page redirections.
Too many irrelevant keywords.
Setting ups pages, domains or subdomains with basicly duplicated content.
Pages without content
Google has an address to report fraudulent website activities:
