pumping at work! help!!

Hey guys! I'm hoping to be able to breastfeed for a min of a year. I'm going back to work in a week and change. I was checking to see what tips any of you have on how to fully empty out your breast. Do you pump for as long as there is milk coming? Do you pump for a certain amount of time, stop then start again? Any advice would be great! I'm a teacher so I'm limited how long I will have to pump. I rather have somewhat of an idea befor going back. Thanks in advance!