My first piece of advice if you will be pumping at work is to practice pumping before you go! No one needs the added stress of trying to figure it all out the firs time around, in between meetings and conference calls!
Thanks to the ACA you can get a free breast pump through your insurer, so make sure you get one early on and practice while on leave so you get comfortable with it. I got a Medela pump through my insurer. I also have a manual pump which I also recommend you get… you can read all about why I love my manual pump here.
Build a stash of emergency milk. Before I went back to work, I started pumping and freezing milk, bags of about 2-3 oz each. This will help if I ever don’t produce enough milk, I can unfreeze the milk. (But make sure to add to the stash if you unfreeze). I like these Lansinoh bags for storage.
Know your rights! You have the right to time to express milk, and you have the right to pump in a place OTHER THAN THE BATHROOM. Read more about break time for nursing mothers here.
Figure out where you will pump before you go to work. If you can, try to find out what facilities are available before your first day back, that way, you will not be stressing out about this on the first day back. Pumping at work shouldn’t be stressful, but many time it is, and stress can harm milk production.
Another great accessory to consider getting is a Hands-free bustier: This is a great one from Medela.