Whenever you meet clients from a foreign country you have to be aware of cultural differences, patterns of behaviour, beliefs, rules, techniques and institutions characterising the country in question.
Business manners encompass linguistic behaviour: besides the appropriate phrases you should be able to find the balance between talking too much and too little. Conversation is culturally sensitive. Are you a good conversationalist? Are you aware of safe, delicate and taboo topics?
Here are some Business English coursebooks that you might find useful in this respect:
