1. keep parameters to less than 3
2. No Session ID's in URLs (common to most php and out of the box carts)
3. Avoid using ID or ProdID or something similar as a param
4. Avoid using product descriptions as link text
5. Pages with less than 300 words of copy are harder to place
6. Pages with less than a 60/40 split on text in copy to text in links will be problematic even if there are over 300 words of copy

Can you still get pages with these characteristics to place. I would say yes to all but 2 & 3. Even 3 will occasionally get placement but at some point they almost always end up in the supplemental index on Google. Maybe not immediately but... eventually.

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