Know the signals your body may be sending and be careful when interpreting theirs
Body language and nonverbal cues can be interpreted differently in various cutlures
Nonverbal Communication and Body Language: Safe Skills
Eye contact is a very powerful yet unconscious means of communicating, and the way it is used varies across cultures, sometimes dramatically. In Asia, for example, less eye contact is preferred than in the U.S. and Europe. In the Middle East, more eye contact is preferred. Keep in mind that your counterpart's natural style of making eye contact may differ from yours, and remember not to interpret it as something negative. For example, don't read too little eye contact as lack of interest or a sign of deceit, and don't read too much eye contact as invasive or aggressive.
Since in many cultures one's posture communicates respect or a lack of respect, it is best to always sit properly. Avoid leaning back, slouching, crossing a leg over a knee (knee over knee or ankle over ankle is okay), draping your arms across furniture, stretching, etc.
Shoes (and sometimes outerwear such as coats and hats) are considered dirty and unpleasant in many parts of the world. If your host ever suggests that you remove your shoes, it is obligatory to do so. If slippers are offered, wear them.
Remember also that you should never extend your feet or show the soles of your shoes to another person; do not point with your feet if your hands are full, and do not move briefcases, boxes, etc. with your feet.
Never blow your nose in front of others, especially at the table. Always excuse yourself.
A good rule of thumb for hand gestures is, "Don't!" Okay signs, V for victory or peace signs, thumbs up and all sorts of other symbols can be meaningless at best and possibly obscene.
When pointing to indicate a person, thing, or a direction, use your whole hand and not just your index finger. To beckon a person, wave your open hand starting away from your body and sweeping inward towards you.