I'm not an SEO person by any means, but you may want to look at a few things on Google's site:
1. see
http://static.googleusercontent.com/external_content/untrusted_dlcp/www.google.com/en/us/webmasters/docs/search-engine-optimization-starter-guide.pdf for their "starter guide" that contains basics of good site practices.
2. Google's webmaster tools (
https://www.google.com/webmasters/tools/home?hl=en). if you verify ownership of this site, you can get info about how google sees the site, get info about any crawl errors, get html suggestions, etc.
3. in addition to #2, you may want to set up Google Analytics (
http://www.google.com/analytics/) to get info about visitors and how they're ending up here (search engines, referrer sites).
Unlike the usual sites in need of SEO help, CT has no shortage of high quality, useful, and unique content. So it's about making sure people who are looking for this content can find it.
As I said, this isn't my area but from what I know here are a few things you could consider:
1. You could look at those sites where users are looking for and can't find good HA content: do they show ads? do they show ads from any of the major ad networks e.g. Google Adwords? if so, you could consider experimenting with some keyword-based ads and see whether any of them give you a measurable return
2. Look at some of the more active areas on the site (the tutorials, manufacturer subforums, show reports, Premise downloads, etc) and work on promoting that content specifically: you could experiment with keyword ads as above, or provide more explicit pointers to some of this content via Twitter and facebook (i see CT has a presence on both Twitter and facebook, but i didn't see any recent Twitter content, and the facebook wall appeared limited to summaries of recent posts; you could also post pointers to content that a casual observer may not easily find on the site). And, of course, you could also join Google+, they recently added support for businesses (previously was limited to individuals).
At any rate, there are probably other folks here who are more experienced in all of this, but I hope this helps.