Avoid slang and colloquial language, often such phrases are regional. In the U.S., for example, language is replete with sports slang ("slam dunk,""home run," "scrimmage," etc.). This doesn't always easily translate to other countries.
I agree with deblipp. I'd also avoid comparisons that involve public figures such as politicians, and celebrities because you can't be sure of a different cultures impressions of them. Watch out for assumptions that might not be universal, especially in the business world. Many cultures have different views on time, norms and etiquette.