What to do in Berlin?

I am from Hong Kong, and working for French logisticsd company supposed to transfor to work in France from May Protected content .. but because of all different reasons.. I am ready to leave Hong Kong, but the company didn't get my working permit ready. So I am landed in Berlin and start my 3 month long holiday here.. but what to do? I think I can use this three month to:
1. Learn German if I can find a language partner to exchange by teaching Mandarin
2. I can be a Chinese tour guide if some one need it
3. help some company or business if they need logistics and transportation advise for trading between Asia and Europe?
Any adivse???