Amazon is a well-known established website basically when people want to search something they just key-in amazon ranking usually depends on organic search. As for you if your website is relatively new then you will need to create backlinks for your website.
Please friends really need your help.
Can you please suggest me some most effective off page SEO activities which can work for my clients.
You can always do forum participation with quality forum websited that has a direct relevant to your products/service. Social bookmarking also work. Then create a fan page wherein you can make an update from time to time.