I've noticed my search ranking slipping in recent months so I'm trying to find ways to improve my site and ensure all pages and content are optimised. My site is set up with canonical URL's but I'm not sure if they are set up ideally in terms of best SEO performance. I have static product pages with the canonical URL's hard coded, but it occurred to me that this does not allow for the URL extensions to be added such as '?pg=2'. My proddetail pages are coded to take the URL from the server, but this does not include the URL extensions such as '?review=all'. Would it be best to include these URL extensions on canonical URL's and if so can you advise what code I would need to use the generate this.

Thanks,

Richard.