How to optimize an eCommerce site for Short tail keywords?

Hi,

I’ll be optimizing an Ecommerce site for seo from scratch. But the project owner wants to rank on 1st page of google for their top 20 keywords which are two phrase. They are spending hugely on adwords through which their traffic is good.

What strategy should i make to optimize for two phrase keywords? How?

Thanks in advance.

If they are competitive keywords and I believe that better in this situation is to hire someone for this job.

do link exchange with similar content website using focus keyword as link text. It would be better or hire a good seo specialist.