You also have to design around multi languages as well, as words in other languages might be longer and could break your design.
Well it would be a e-commerce site...
and a language button somewhere in the menu.
I figure you set up the site in one language (french in pur case)
One complete, we send the link to the translation team so they can translate to English. (we do this with concrete 5 site for example).
Same for EMail marketing.