If you want to SEO page contents you need 1st to apply Google Webmaster guidelines (at least the basic guide) to your dynamic generated pages, therefor you need your dynamic page to set properly in page at least the <title> and <h1>, <meta description> by retrieving this contents from the DB. It should be different for each page, Google seems to dislike repeated contents and final users dislike them too.
Then if you want to SEO page URLs, you basically needs to make URLs more human readable, as for a very general example: if a page talks about 'cats' the url should be something like: http://...index.php?id=cats (or maybe better http://.../cats) just avoid http://...index.php?id=54637
In order to accomplish this task here they suggested me to create in DB table an alias field for each item/article, so supposing your DB primary key is an integer just cerate a another field called 'alias' (this field muts be UNIQUE no duplicates, as for the primary key) and use it in your URLs.