If you are targeting a specific geographical market you need to be sure your site will be accepted not only by the international engines but also their regional versions as well as the smaller regional-only engines and directories.

Most web users will use an international engine as well as a local one so do not discount the international engines and directories. But you will also need to be listed in the regional engines. To ensure the regional engines and directories will index your site you will need to make sure that the geographical focus is extremely clear by using a country specific domain, language (don't have a site in American English if you're targeting a French audience) and contact details.

If you have several sites targeting different geographical markets you should ideally have a unique site for each country complete with the correct domain suffix, language and local contact details. This is not only for the engines but for your prospective audience as well.

Find a local SEO expert and copywriter - straight translations will not work. Believe it or not you cannot simply translate your meta tags into Spanish and hope to be accepted by all the Spanish language engines. You need to outsource the optimisation to a native of the country you are targeting and the keyword research will need to be specific to that country, not just that language. French Canadians and European French use different terminology as do the Spanish and Mexicans and British and Americans.

How Search Engines Regionalise
Optimizing for International Search Engines
WebmasterWorld's European SEO strategy primer #3
Webmaster World UK and Ireland
Webmaster World European Search Engines Forum
Search Engine Forums: The UK and Beyond
Search Engine Forums: Non English Search Engines