Hi everyone..=) some tips please

hi..

My name is charry..Im here in london and il be travelling to sydney next week for 9 days..

I know I had very limited time but still want to make the most of it..

any suggestion or tips?

and what are the places that I MUST go to or activity that I MUST DO..to culminate my stay=)

thank you=)

and addition to what are the best souvenirs I can buy from australia without getting in trouble with the border agency or custom..and where to buy them from..thank you..=)