Here is the redundant list of what u r recommended to have before DIY:
1. Two 4 feets and two 2 feets fluorescent tube, if u want side, front and back.
2. 4 ballast - 2x 20w and 2 40w DC choke.
3. Wiring - lasting power cable, length is depend on ur wiring map and car size.
4. 10amp fuse.
5. Fuse holder.
6. Switch to on/off the light.
7. Fluorescent tube holder (Used to connect the 2 pins on fluorescent tube to cable one, and hold it in place NOT ON UR CEILING ONE) .
8. Cable lug to connect wires.
9. Steel band for undercarriage mouting. Cable tie also can but not long lasting.
10. Wire insulator.
11. Voltmeter.
12. Cable tie.