I have a potential client with a several hundred page ecommerce site (OS Commerce). Any tips on the best way to approach shopping cart sites like this with each page having a related set of products?
You can check out my site in my sig. With sites like this SEO is very easy becase you only have to optimize one or two pages of code to make the whole site SEO optimzied.
Hundreds of pages, but what I think he means is that they are all dynamic views generated by one php file. So you can just edit the code in that file and optimize it. One thing I would recommend is getting them off of oscommerce - updates are few and far between. Take a look at zen cart or Magento, I've had better success with using them.
Oh I see. But don't I still need to go in and edit titles, meta tags individually or is that handled through some central web interface with oscommerce?
I don't think os commerce handles it out of the box - I think you have to download their SEO module add-ons and install it by modifying the source code, which will make custom titles and meta tags from the product title and description. You should also install their SEF (search-engine friendly) URL module. This is why osCommerce is an outdated system -Zen and Magento support these things out of the box, without having to manually modify the source.
First onpage SEO is basic stuff that you must absutely do, there is a SEO module in oscommerce use it and hire a writer to write long quality descriptions (Seo text) for each of those pages, and yes you still need to go in and edit titles, meta tags individually (via the module), the module will help but it can't guess your optimal keywords and titles, you should analyse and research the optimal keywords for each product/page, then optimise the pages for those keywords. Now about link building..you need to focus on building an authority website, this way all the internal pages will rank automatically, you still need to get some deeplinks but when you have a website with thousands of produtcs and pages, it's very hard to optimise those pages one by one, so your best bet is to build a very Strong backlinks profile for the main homepage, and in the same time you need to build very good and smart internal structure, once the website become very strong the internal pages will also rank very well, also try to link to as many internal pages from the homepages as you can , if the design allow, link to as much as 150 or 200 internal pages (the most important products) from the homepage, this is really a very important factor and it will help those pages rank better. if you dont know how to do that without ruining the look of the website, then take a look at www.wigs.com for example, they link to about 150 or so internal pages from the homepage, but the design and implementation is very nice so everything is cool. Good luck.