Use italics to delineate foreign words that have not been adopted in English. Don't use any formatting or punctuation to delimit words that have been adopted in English.
If you're giving a translation of an English word, use the same format as for Foreign-language names. For example:
Alternately, you can use the foreign language word, and provide the English translation in parentheses but no italics afterwards, as in:
If there's just no translation for a foreign word, or the word has been explained already, just use it without a translation.
See also: Wikitravel:foreign-language names, for proper nouns