Several things can go wrong, however especially if you have different portals for the same language countries, i.e. America, UK and Ireland.
You will want your UK site (mysite.com/uk/) to get Google's sitelinks to UK pages. The international set up should aim to produce different site links for each XML International of the countries as well as show different language/countries website versions for different country users.
International website objectives:
Encourage the relevant versions of the site are being shown in all countries accordingly, for example, mysite.com/uk/ for the UK and /us/ for the US.
Encourage correct sitelinks being listed for each of the countries, see Apple.com/uk/ for an example.
Ensuring correct international indexing:
- Make sure that each country section of the site is clearly marked as such (country tags in HTML, clear text links, clear and obvious navigation, use local currency/date/measurement formats).
- Add a link tag to the header of the templates to tell Google the corresponding homepage for any given portal. For example, on the UK portal.
This should be placed in within the head area of the HTML page.
- If you have different physical addresses/phone numbers for each country, list them clearly in the relevant sections.
- Go to Google Webmaster Tools and verify each country's subdirectory/portal as a site. Use the geo targeting option to set each subdirectory to the relevant country. See the next section for clear instructions.
- Create separate HTML and XML sitemaps for each country. Submit these XMLs.
- Get good quality incoming links from UK sites to the main UK pages, quality US links to the US pages, and so on.
Google Webmaster Tools for International sites
Firstly the mysite.com should be set up as the main domain.
Secondly, each of the portals should be added individually as websites in the Webmaster Tools Account. Only the top-level domain has to be added and verified, the remaining portals will be automatically verified because they reside underneath the top-level domain.
Each of the country portals should have the corresponding sitemap uploaded and submitted to Webmaster Tools to tell Google which pages belong to the country subfolder and as a result which pages to show to the users based on their geographic location. Separate sitemaps should also be created for each country portal to see how Google is indexing those URLs.
The geographic location should be set up in Google Webmaster Tools accordingly for each country.
Gaining correct sitelinks
- Make the pages that you want in sitelinks are ranking #1 in Google
- Make sure these pages have HTML (not JS, FLASH, etc) text links from the homepage.
- These pages need visitors clicking on them from the search results (CTR) and from inside the site.
- You can always delete the incorrect sitelinks and wait for Google to replace them with the correct ones.
Finally, it makes the most sense to hire an SEO agency, XML International which will manage your international SEO rather than having several SEO agencies for each country. You risk having your UK SEO agency building links form American sites and as a result the portal, which has the most American links, might rank better in America, whether it is an American or UK portal.