Need modules for multi languages

I need to make my site multi languages.

Any one can give me some advice?  or recommend some language modules?

I think It will cost a lot time.

How can I handle the work more efficient? 

thanks a lot.

languages needed:

English, Chinese (Mandarin), French, Spanish, Portuguese, German, Japanese, Korean, Arabic, Hindi, Italian, Russian and other languages (not important)

I can point you to my module for german language, https://www.boonex.com/m/german-translation-pack-for-dolphin-7-2

Adding language packs is fairly easy with Dolphin.  If you have added custom language keys, then you will have to add the translations for them once you install the language packs.

@geek_girl  @panansystems: Thanks a lot.

I already find Spanish, German, Russian,  and French.

I need to handle Chinese by myself.

Is there a decent mod that just has a flag selector? I will also need this sooner than later.