Cross-cultural communication is a valuable but difficult skill. The most obvious barrier is language, but verbal communication is only a small part of how we convey information. Tonal -- the pitch and speed of one's voice -- and non-verbal communication make up as much as 93% of our total communication. All of these factors are influenced by culture, and the meaning of certain tones or gestures can differ from one culture to another. In a culturally diverse situation, with people of various cultures, the communication barriers are even more complex.
A language barrier to effective communication, even when everyone is using the same language, is the use of colloquialisms, idioms or expressions. In informal English, there are many expressions that do not mean what they sound like. Some examples are "What's up?" or "to get the hang of it." Avoid cultural or pop culture references, since these can be both difficult to understand and alienating. Some tips for effective cross-cultural communication are to speak slowly, speak clearly, avoid long complex sentences, use different words to say the same thing and take pauses.
Different cultures have varying levels of formality in different situations. For example, in North America, business interactions are usually more formal than between family members. However, in many other cultures, business interactions are based on a personal relationship; therefore, the communication is much more flexible and informal. Meanwhile, speaking to parents or elders may require much more respect and formal communication than North Americans would expect. Take the time to observe and ask questions about the social and cultural norms when you are presented with an unknown cultural milieu.
Much of what we communicate is through gestures, facial expressions, posture, eye contact and touching. For some cultures, the sense of personal space is very different, and standing close or touching when speaking is the norm. Eye contact can also convey a great deal, and for some cultures, too much eye contact is considered rude or aggressive. Facial expressions such as smiling or furrowing the eyebrows may be used differently depending on the culture. When communicating in a culturally diverse environment, be aware of these differences and do not jump to conclusions if someone reacts in an unexpected way.
The hardest things to adapt when communicating in a culturally diverse situation are the values associated with culture. You can easily change your posture or stop using slang, but you can't change your core values, or expect others to change theirs. What you can do is be aware of your value system and how it influences your communication. You also need to understand the value system of the person you're communicating with, and how it might affect the way he perceives your communication.