Try to use Flash only where it is needed. Many rich media sites such as Google’s YouTube use Flash for rich media but rely on HTML for content and navigation. You can too, by limiting Flash to on-page accents and rich media, not content and navigation. In addition to making your site Googlebot-friendly, this makes you site accessible to a larger audience, including, for example, blind people using screen readers, users of old or non-standard browsers, and those on limited low-bandwidth connections such as on a cell phone or PDA. As a bonus, your visitors can use bookmarks effectively, and can email links to your pages to their friends.

Link: Best uses of Flash

Words matter. They always have. They always will. On the Web, words matter even more. The right words.

…If you want to design a new website, the first thing you should decide on is the words. Not the graphical design, not the software. No. The words must come first. Once you get the words right, you are half-way there.

Link: Your website: Just words?

1. Keyword research
2. Get some (trustworthy) advice
3. Look after your code
4. Make navigation easy
5. Get links
6. Build a sitemap
7. Don’t forget the technical stuff
8. Track your progress
9. Tell the search engines where you are
10. Content is king

More at this link: 10 Top Tips to Make your Website Search Engine Friendly