If your Japanese clients are able to understand English but not very well, sometimes you may like to speak with your Japanese clients without the help of your interpreter. When you understand the basics of Japanese, you can use this knowledge to make yourself more comprehensible when you speak to Japanese people in English. Because of the grammatical structure of Japanese, some things in English are going to be hard for them to understand -- just like some weird Japanese constructions are hard for Westerners to understand. Then how to make you understood? Here are some tips:
Avoid negative questions. Negative questions
are used for politeness in Japanese, and the answers are
sometimes the opposite of what is conventional in English.
So asking, "Don't you have any water?" is more polite than
asking "Do you have any water?" in Japanese, even though
the former sounds a little more abrupt in English. Furthermore,
these questions are answered in Japanese by answering the
truth or falsehood of the word "don't". If you do have water,
the answer to the first question above is "No" (I do), and
if you don't have water, the answer is "Yes" (I don't).
This is just way too confusing for everyone involved. Do not ask negative questions to Japanese people in English. Don't say, "It's getting late-- aren't you going to that movie?" or "Didn't you say you were from Hokkaido?"
Limit the use of relative clauses. Take
a look at the chapter on Adjectives. Japanese adjectives
always come before the noun that they modify, even when
they are adjectival phrases and clauses. English is much
more confusing: we put plain adjectives before the noun,
but phrases and clauses after the noun. Thus, we say "the
blue chair," but also "the chair that John was sitting in."
Cases like the latter are hard for Japanese people to hear,
especially if the phrase gets really long. Try to avoid
saying things like, "That's the car that I was planning
to buy last summer when I had money from my university job."
Particularly bad are sets of embedded relative clauses. For instance, "I thought that the book he was reading, which looked long and dense, was probably for the new law class he is taking."
More generally, try to avoid putting long qualifiers after the main idea in a sentence. Japanese sentence construction always places the independent clause at the end, as the final clause. In English, we have the freedom to put the independent clause in other locations, which can be confusing for Japanese people. So after you've said the main idea, don't add a bunch of other stuff. This would be a bad sentence: "Yesterday I bought my sister this camera-- which turned out to be a bad idea after I realized my mom had already bought one because her birthday is coming up next week." (This sentence has other problems too, like the excessive use of pronouns. Remember that pronouns are a lot less common in Japanese. Try to avoid pronouns that don't have really obvious references).
Do not use lengthy "or" constructions. If you give a Japanese person a complicated choice with the two parts separated by "or", you will almost always get the answer "yes." For example, "Do you want to try windsurfing even though it's raining or would you rather spend the day at the museum"? Answer: "Yes." (The reason for saying "yes" is that the person hears their choice somewhere in the complicated phrase that you said, so they just agree and hope that all the stuff they didn't catch wasn't important).