You can express your breastmilk by hand or with a breast pump. This depends on what you feel comfortable with and the needs of your baby.
For an occasional feeding, express by hand. This is usually easy and needs no equipment. If you prefer, you could use a hand pump.
When you are expressing breastmilk for a premature or sick baby, a hospital grade electric pump is the best choice. Pumping both breasts at the same time works best.
Do not use a pump with a rubber bulb. The rubber bulb is hard to clean and may damage your nipples.