Google has been trying to understand flash websites but the algorithm is still in its infancy. I have never seen Flash websites get optimized and ranked easily. Also, its Google who did some efforts to get flash onboard back in 2008. Since then... no news from Google... and take of other search engines on flash is completely unknown. Get rid of flash...
I would convert it to HTML or something similar before attempting to optimize a website, especially if the keywords are competitive.
Try to look for a blog that discuss about how to optimize a flash site. There has been lots of article already about optimizing a flash site.
First of all let me say one thing. Websites using Flash, Flex are not Search Engine Friendly. Doing seo for these kind of websites is little bit difficult than normal html sites. The main problem is the URL optimization.
flash sites are horrible when it comes to SEO. however if i remember correctly, you can set web crawler readable text in flash layouts. so make sure you do that.
Flash sites are very much out of date. Much of this has been replaced by Jquery which is a bit search engine friendly. But FLASH cannot be properly SEO'd.
Following are some of the methods to optimize a Flash Website Input metadata This is a very important approach, although it is often underestimated and misunderstood. Although metadata is not as important to search engines as it used to be, Flash development tools allow easily to add metadata to your movies, so there is no excuse to leave the metadata fields empty. Provide alternative pages For a good site it is a must to provide html only pages that do not force the user to watch the Flash movie. Preparing these pages requires more work but the reward is worth because not only users, but search engines as well will see the html only pages. Flash Search Engine SDK This is the life-belt. The most advanced tool to extract text from a Flash movie. One of the handiest applications in the Flash Search Engine SDK is the tool named swf2html. As it name implies, this tool extracts text and links from a Macromedia Flash file and writes the output unto a standard HTML document, thus saving you the tedious job to do it manually. However, you still need to have a look at the extracted contents and correct it, if necessary. For example, the order in which the text and links is arranged might need a little restructuring in order to put the keyword-rich content in the title and headings or in the beginning of the page. Also, you need to check if there is no duplicate content among the extracted sentences and paragraphs. The font color of the extracted text is also another issue. If the font color of the extracted text is the same as the background color, you will run into hidden text territory. SE-Flash.com Here is a tool that visually shows what from your Flash files is visible to search engines and what is not. This tool is very useful, even if you already have the Flash Search Engine SDK installed because it provides one more check of the accuracy of the extracted text. Besides, it is not certain that Google and the other search engines use Flash Search Engine SDK to get contents from a Flash file, so this tool might give completely different results from those that the SDK will produce.
If you really want a Flash site, then you should try with the Action Scripting with XML. It has better chances to have good ranking than a simple Flash site.