I've just picked up a contract to sort out a vipers-nest of e-commerce websites that a previous 'developer' left for one of my clients. There's about a couple of dozen of them using a custom shopping cart and CMS system that's too embedded to dump and works well enough, but desperately needs cleaning up, re-factoring, and bug fixing, so a reasonably substantial recoding job.
As part of this my client is desperate to ensure the best search engine placement he can get. Like many developers I've a nodding acquaintance with the idea, but no real knowledge, and it seems that it would be helpful to get up to speed on this so I can build appropriately into the code.
So can people advise on useful quality resources - books, websites, blogs etc? I do not wish to obsess over every last detail on this (he can use a specialist if he decides to pull every last ounce out - although I've always regarded such as little better than snake-oil peddlers), but I would like to build code and reconfigure templates in a manner that helps rather than hinders placement.
Look at Wikipedia with styles off. See how they order their content? See how they use correct tags to label the content? These are the keys to long term success.
The most important SEO advice is to create a semantic, logical site. The content comes first and is ordered by importance. Use the correct tags, don't do tables. Then apply styles. Then apply script to make it fancy. (Like Tomas said)
Know the difference between what is content (pictures of your products) and not (your logo tiled on the background). Basically do your best to present good content in a good way. You can't game the system for long term gains.
This will give you long term placement. Most SEO companies just do tricks or links farms or worry about keywords and meta tags, so they are temporary at best. I think it is good to assume that Google works just as hard to drop that crap from it's index as the SEO marketers do to include it.
According to Google's patent