Cursing

You are his older sibling so you set the example. He looks up to you. Let him know that swearing is not ok and then follow your own rules. Some people have a coin jar and make kids put in coin (of their allowance) in the jar every time they say a bad word. That seems to work. Good luck!

I think that sitting down and explaining that these words are often insulting and inappropriate is a much better approach than starting off with punishments. The best thing, off course, is to set a good example yourself.

First of all you need to make sure he understands why it isn't good to curse. After you have had a talk with him you should make sure he doesn't get away with cursing when he's next to you. If he does curse you have to mention to him that it's unacceptable to curse.

The most important thing to do is to set an example so make sure you don't curse next to him even by accident.

It depends on his age and the situation. I don't see cursing as a bad thing altogether. Sometimes it is a very easy way to relieve agressiveness, especially if cursing is not aimed at anybody, but as a cry of frustration. 

And as others had already said, there is nothing better than a good example and explaining to him that there are things not acceptable in society.

I personaly cant see any way to stop someone cursing, this day in age. It seems that you cant go anywhere without hearing it, you hear it on TV and radio all the time. Sure as people have said you can ensure that you set a good example, and try to teach him other language he can use. I just realy wonder if it would be enough to stop him cursing?