Use Flash for non-critical pieces of a page (MEDIUM PRIORITY)
The best use of Flash on websites is as small portions of the site, preferably non-critical portions. Search engines can't view Flash, they see them as images. According to Google Webmaster Central, sites that effectively use Flash "use Flash for rich media but rely on HTML for content and navigation."
Keep your pages close to the root directory (LOW PRIORITY)
The higher your pages are in your sub-directories, the better they will rank in search engines. This is because pages that are listed right off the root directory are typically more important than pages that are found four or five levels deep in the site.
Use the meta keywords tag and include your keyword phrase (LOW PRIORITY)
Meta tags are a very popular way to improve search engine results, but the fact of the matter is that some major search engines don't use them at all, and others only use them a little. It won't hurt to include your keyword phrase and any secondary keywords in the meta keywords tag, but don't expect it to work wonders.
Keep your kewords together (LOW PRIORITY)
Search engines rank keywords in pages regardless of where they are found. But if you're trying to rank well for a specific keyword phrase, keeping the keywords together will insure that the search engines recognize that they are related.
Use your keyword phrase in your meta description (LOW PRIORITY)
Most search engines use the meta description field as the description in their search results. So it's important to have a good description. Including your keyword phrase in the meta description tag is one more place that the search engines can see your keywords. This isn't a magic bullet, but it is a good idea.
Set your language meta keyword (LOW PRIORITY)
If your page is in a language other than English, you should set the language meta tag so that search engines (and other user agents) know what language it's in. Most search engines have other ways of telling what language the page is written in, but they do use that tag, and it could help you rank higher in searches in that language.
Optimize for a few secondary keywords (LOW PRIORITY)
Once you have a keyword phrase, you can choose one or two other keywords to optimize for as well. But be careful with these - make sure that the density of your secondary keywords is no more than 1-2%. Any higher and you risk confusing the search engine and diluting the power of your primary keyword phrase.
Use your keyword phrase in named anchors (LOW PRIORITY)
A named anchor (also called a bookmark) is a useful tool for creating navigation within a Web page. But for search engines, it also indicates that the text defined by and following the anchor has more significance. If you use your keyword phrase in some of your named anchors, that will give that text more prominence.
Use different forms of words for your keyword phrase (LOW PRIORITY)
This is also called stemming. Most search engines recognize that one word stemmed from another is really the same word. For example, plural versions of nouns (dog and dogs), gerunds and active verbs (dig and digging), and so on. By using different forms of your keywords, you can make your page more interesting for your readers, while still optimizing for search engines.
Use synonyms for your keywords (LOW PRIORITY)
Synonyms, like keyword stemming is another way to mix up your text for your readers while still optimizing for search. Most modern search engines have a powerful synonym library and so recognize that words like "dog" and "canine" mean the same thing. Be careful using this technique on non-English pages, however. Most search engines were developed in English-speaking countries, and have more extensive English vocabularies than other languages. Also, you should remember that tools like keyword density readers often don't recognize synonyms, so your page may be denser in keywords than they report if you use a lot of synonyms.