Whether you are exclusively pumping or pumping at work, there are a few things that will make pumping easier and a better experience. I am not an expert, just a mama who has pumped to build a supply and while working. These are some of my favorite must have breast pumping items.

Breast Pump
A good pump is obviously an important thing to have. Having a good pump will help with milk production and the amount you pump. I have the Medela Pump in Style pump. It is easy to learn the settings and use. This was a pump I was able to get 100% free through insurance.
Water and Snacks
Water and eating enough calories is extremely important for milk production. Every time I sit down to nurse I get extremely thirsty, so I always make sure to have a bottle of water when I pump too. Eating a good snack while pumping is a great way to get in a few extra calories for the day also.
Hands-free pumping bra
A pumping bra is nice to have to hold the pump in place and free up your hands. When I pumped at work, a pumping bra allowed me to answer a few emails during that time instead of holding the pump in place. This is definitely a must for comfort.