Pray with your interpreter.
One of the things I have noticed over the years is that when I have a good interpreter, we flow in the same anointing. Take time to pray with your interpreter before the meeting. Specifically ask the Lord to take of the anointing that He has placed on you and place it on your interpreter. Ask that the Spirit of God will cause your interpreter not only to understand your words correctly, but to grasp the heartbeat of what you are saying, and to convey it in the same spirit and power.

Keep it relevant.
Particularly if you are ministering in an undeveloped or developing country, the people to whom you are speaking live in a vastly different world from the one you know. Your illustrations must relate to the people to whom you are ministering.

This goes beyond simply not using illustrations that relate to technology or western consumerism. One of my early mission trips included Zambia. At that time I had a pet saying that “some Christians act as if they find Jesus about as exciting as a sack of dead mice.” I used it, without thinking, in one of my sermons. It was only later that I realized the people of that area ate mice, and a sack full of them would probably have been a very exciting prospect! I can only assume I had some very confused listeners!

Matters of style
When it comes to style, there are a few things western preachers really like to do but which simply do not work in a message that has to be interpreted.

Firstly, forget about alliteration. Some preachers like to help people remember our messages by giving them major points all starting with the same letter. In English, it generally works well – even though some of the contortions used to achieve it at times can be rather grating. In other languages, it doesn’t work. Period. Your carefully selected words, even if they can each be translated by a single word, will all begin with different letters.

Worse, if your interpreter figures out what you are doing and tries to alliterate them in his own language, you could end up with something that is not quite what you are actually trying to say. Far better simply to make clear, concise points and trust the memory capacity of your audience.  

Likewise, avoid slang. At best, it will not be understood. At worst, it will be understood as meaning something vastly different from what you had intended. In fact, that can happen even without going to another culture.

One of my most embarrassing ministry moments came, not on the mission field, but on the other side of Australia. In the course of a sermon I used a slang term I understood to mean something totally innocent. Afterwards the pastor drew me aside and asked what I meant by it. I told him, and he told me what it meant over there – I had unwittingly used an expression that was offensive in the extreme. Ever wished the ground could open up and swallow you whole?

Forget jokes. Humor generally does not translate cross-culturally. There is a story, allegedly true, of an American evangelist who was conducting a series of crusades through Asia. His policy at home was always to open his message with a joke, and he did the same when he was in Asia. He was delighted that every time he did so the congregation roared with laughter, and returned home to tell his family and friends how much the Asians had appreciated his jokes. It was only some years later that he learned that, in every instance, the interpretation went something like this: “Our brother is about to tell a joke. You will not understand it. Please honor him and laugh when I tell you.”