Same posts in different languages, how to ?

Hi,

I would like to have a blog in two languages.
How can I achieve that ?
I was thinking if to have a language selector and the entire to switch to selected language, or to be a default language and in the front of the post title or inside the post to have a switch between languages.
Now regarding the posts input, should I make 2 different entries for each post, or there is a way to add both of them into the same posts but insides some tags <language=en> .. </language=en> for example ?
I’m waiting for advices and suggestions.

Thanks.