You will need:
1. A Raspberry Pi of course. You will also need a Power Supply Unit and a case.
2. A USB keyboard, a USB mouse, monitor with an HDMI connection and an HDMI cable.
3. An SD card reader.
4. A USB Stick for data storage although this is optional as you can use the SD card for data storage.
5. An Ethernet cable to connect your RPi to your Router / Wireless Access point or Ethernet Switch.