Boosting breastmilk supply!

What is everyone doing to boost there breastmilk supply? I have to go back to work in a month and I want to get a stash going. Right now I breastfeed and also pump and do bottles. I usually get 4 oz each time I pump but that just replaces the bottle I used. I want to produce enough to freeze. What are somethings your doing to boost supply and how many ounces do you get/how often do you pump?