Bilingual site is a revolution for bloggers
How to make a bilingual site
I wanna ask you first, what is your website‘s main language, does your site is a bilingual site? Is it English? If it’s English, you can go to the other post. If not English, you should read this post. English is international language, and you may find your competitors site use English as primary language. If you don’t believe it, just go to Google and type anything you want and you will find the most numbers of site shown in Google is an English-language site. You must use English in your site, but I recommend you to use more languages on your site. Use your native language and English.
Here are some guides to make a bilingual site from http://poplarware.com/downloads/language_switcher :
The Language Switcher WordPress plugin allows you to create a bilingual or multi-lingual blog or site, using WordPress. The way it works is that you write the content for your site in multiple languages, using special tags to tell the plugin which text goes with which language. You’ll also install “gettext” language files to translate the text generated by your theme, other plugins, and WordPress itself into your target languages. The Language Switcher plugin will then let your site viewers choose a language for viewing your site, and put all the text on the screen into the right language.
Unfortunately, setting up a multi-lingual site does take some work. You will need to follow all the steps on this site carefully to get your site functioning properly, and it will require at least a passing knowledge of WordPress and probably HTML. Also, unfortunately many WordPress themes and plugins that other people have written are not set up properly for internationalization and multi-lingual sites with the Language Switcher. Instructions are given on this site on how to fix them, but it will require some PHP programming (or at least PHP editing) to fix some plugins and themes. So, be prepared! The good news is that the core of WordPress has a lot of functionality, and the Language Switcher works well with the core WordPress functionality.

Note: Language Switcher does not do any translations! It just allows you to display text that you have provided, in the language preferred by your site’s visitors. There are other plugins that can be used to create multilingual sites that have different approaches, including automatic machine translations. To find other plugins, see the Plugins article at wordpress.org.
Like my blog, I’m using English as primary language but I’m a Indonesian. Don’t mind if your English is bad. Just do it, then you can get a very unique content for your site. Make your own language style and you will get a traffic. Do it with style! Oh, one more thing, create a unique word and use it in every post of your bilingual site.