SEO is the most important part when maintaining a website, especially if you would like it to have an international reach.
Aleyda Solis has published on MOZ’s webiste the following International SEO Checklist, which in my opinion is very explicit and straight-forward, in order to target international audience and the development of an internationally targeted site:

seo-check-list-international-target-audience
source: http://moz.com/blog/the-international-seo-checklist