Keeping It Simple is something that as a site grows and develops becomes harder and harder. A great example is this very website. No doubt if you have visited for more than a month you will have noticed I on a regular basis change my theme (though previous to this theme I had a theme for 4 months just changing the colours not the theme). The current theme has been my most successful theme and so from next week will be available for download (we are just adding a few more SEO features).
Another change some poeple have noted is a change in tone of my articles, it is less blunt and more flowery... now this is done with some good reasons including; it is easier to read, easier to remember and the content to some extent is easier to understand. But this doesn't mean that it is good for SEO. Indeed pretty much far from it! If you have flowery content you are showing search engines a level of complexity, as you are if your theme is full of code and your content is hidden amongst it!
There are pro's and con's of your theme and copy, add to this no 2 websites are the same in respects to what works best and you will understand you will have to do a little experimenting of your own to find the best results. To help you along the way I have put together my KISS ME list of do's and don'ts.
KISS is the normal, Keep It Simple Stupid ... ME is my own addition My Experiments
Title Tag - Should be unique on each and every page. It should include a keyword or two & if possible your company/brand name. You should consider this your primary pull from a search engine results... a brillinat call to action may help.
Description Tag - Must be unqiue on each page. It should explain in a short blurb what this specific page is about. It is part of your search engine pitch to visitors ... get it right and you make money...get it wrong and you will be ignored.
Keywords Tag - Should really be unique though a few over-lapping keywords/phrases may help enforce your company or brand name. You should consider having an ideal number of keywords between 7 and 10.
The Copy (The Content)
Heading Tags - H1 is used by Google to define the main "keyword focus" of a web page ... without it you may struggle... using more than one and you will struggle even more. You should used H2, H3 etc to clearly define sections of your content ... Google is known to use Heading Tags to define keyword focus areas.
The Script - Must be unique, informative & useful in meeting the needs of your users/readers.
Links - Both internal and external links should be absolute.
Breadcrumbs - Are of use if you have multiple directories of content.
URLs - Should be non-dynamic and easy to read / remember format.
SiteMaps - Both user readable and machine readable are important.
Robots.txt - Files are very important, use them to point to sitemap(s) and tell search engines where they can and can't go!
Redirects - if a page disappears (for any reason) use a 301-redirect to point to the next relevant page (or the new page) ... also use the 301 to force users and search engines to either www. or non-www.
Clean Code - Don't waste your own time or the search engines time...if you can't understand your code the chances of a search engine understanding it and getting to the content are none!
Analytics - getting metric data for your site is important, if you don't have your own server stats (or even if you do) you may want to consider using Google Webmaster Tools and Google Analytics.
Experiement! - Play around and have fun with your sites code and content and how it looks... get all 3 right and you will be onto a winner... get it wrong and you will suffer... nothing is 100% perfect but you can get damn close if you experiement.