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Yes, making the links nofollow should be implemented. BUT... I will say that outgoing links are not generally a bad thing, unless that's all there is to the site. If all you're doing is publishing affiliate links without any content then I wouldn't expect to give up your day job any time soon to retire to the Bahamas... Affiliate sites that do well, do well because the people running them provide decent content and add value. Just my twopenneth... I am not suggesting that this is your plan, just that that may be the reason you've heard that outgoing links are 'bad' for SEO. In fact, Google is more likely to recrawl more often if the site is both easy to crawl and is not a dead-end (in other words a site with no links would probably not be crawled very frequently), so it could be argued that outgoing links are a good thing. Personally, I would use magento over wordpress - it's more secure and less likely to get hacked. I hope this makes sense! Good luck with your venture.

Thanks all for your help and advice , really appreciate that !