Google Do's and Don'ts

While giving more clues about the latest Google 'Bourbon' update, GoogleGuy has also talked about a few important things that should be done or not done, when optimizing your website for Google (but not only for Google).

I've been aching for a long time to mention somewhere official that sites shouldn't use '&id=' as a parameter if they want maximal Googlebot crawlage, for example. So many sites use '&id=' with session IDs that Googlebot usually avoids urls with that parameter
And then

I've never heard the suggestion that Google would penalize for iframes before reading it in the thread. Plenty of legit sites use iframes, so it wouldn't make sense to penalize for it. Powdork gave the right response in message 337 of the first Bourbon thread. Now I can easily believe that some search engine spiders would have trouble with iframes just like some spiders have trouble with frames. But I wouldn't expect iframes to cause any penalties.
And finally

My rule of thumb is to pick a root page and be as consistent as possible. I lean toward choosing http://www.yourdomain.com/ but that's just me; http://yourdomain.com/ would work as well. Then I recommend that you make things as simple as possible for spiders. I recommend absolute links instead of relative links, because there's less chance for a spider (not just Google, but any spider) to get confused. In the same fashion, I would try to be consistent on your internal linking. Once you've picked a root page and decided on www vs. non-www, make sure that all your links follow the same convention and point to the root page that you picked. Also, I would use a 301 redirect or rewrite so that your root page doesn't appear twice. For example, if you select http://www.yourdomain.com/ as your root page, then if a spider tries to fetch http://yourdomain.com/ (without the www), your web server should do a permanent (301) redirect to your root page at http://www.yourdomain.com/

So the high-order bits to bear in mind are
- make it as easy as possible for search engines and spiders; save calculation by giving absolute instead of relative links.
- be consistent. Make a decision on www vs. non-www and follow the same convention consistently for all the links on your site. Use permanent redirects to keep spiders fetching the correct page.

Given that GoogleGuy is quite talkative, in this period, we should probably expect more revelations soon.