Answer : The ultimate trick to raise more easily the minerals you need in the factory of World350 ! 

Have a look at the bottom left side of the screen and you will see a clock and a shield. The shield gives you the power to select the minerals so that you can collect the ones that are key for your next building. The clock gives you the power to slow down time so that you have more time to collect the minerals.

Be careful! as those two powers are limited in time OR are temporary.