When you are a student from oversea, you are holding student authorisation or called student visa.
That authorisation prohitbits you to work at anywhere outside the school stated in the visa. i.e. you can work in your university's cafe and get paid ( legally ) if you want but not restuarant in chinatown.
If you wanted to invest in a company ( of course getting paid ), you must visit the immigration office and obtain a working authorisation or called working visa before you can get paid.
But there are tricks that you can get paid outside school and get paid legally. For more information, please contact me.