What extra shall we do to increase organic traffic for both the sites?

[CyrilWilson]

One of my clients has english language websites targeted for USA and UK audience with some content variations but60%-70% of the content on site remains the same. The site is hosted in USA. One is hosted on brandname.co.uk and one is on brandname.com. The precuations that we have already taken to save it from being marked duplicates are: 1. used rel=alternate element for all product detail pages2. currency in both the sites are different that is GBP and USD3. have tried to differenttate the product by using different product specific terms like Publishing Year: vis a vis published in:Author Vis a vis Written byFormat vis a vis binding type Add to cart vis a vis add to basket and so on

What remains the same:

1. Title structure

2. Description

3. Product Name

4. About the product text

[WSPL]

Despite those changes to the details of both sites, it sounds as though the most important parts of the website are still identical. Although you have used synonyms on small throw-away lines, the bulk of the actual content and wordcount are still the same. To avoid penalty I suggest you consider paraphrasing the product text and description, and continuing your use of synonyms in the titles too.

In answer to your original question about what you can do to increase organic traffic, the answer is always original content. Create infographics, helpful articles, and/or amusing product-related pictures, and distribute them using social media.