Most single coil pickups only have two wires. A negative / start lead and a positive / finish lead.
The negative lead needs to connect to the common ground circuit of the guitar, which is usually the back of a potentiometer.
The positive lead connects to either your pickup selector switch or the input lug of your volume pot, dependant on how your control circuit is wired on your guitar.
Sometimes the pickup will have two physical wires going out of the pickup. The black lead is the negative and the other wire, which may be various colours to denote the pickups position, will be coloured.
If you think there is only one wire coming out of the pickup this will actually be a twin cored wired. The outer section of the wire is the negative and the inner core of the wire is the positive.
Most of our humbuckers follow a standard wiring colour code as follows
Bare wire – this is the overall earth wire and needs to be connected to a common ground / earth point. The earth loop on the guitar can be connected into on the back of one of the potentiometers.
Black wire – this is the negative / start of coil 1
White wire – this is the positive / finish / hot out of coil 1
Red wire – this is the negative / start of coil 2
Green wire – this is the positive / finish / hot out of coil 2
To wire them up as standard humbuckers ( both coils in series ) connect the black and bare wires to a common earth point. This is usually the back of a pot.
The red and white wires come ready soldered together. These are the links wires between coils 1 and 2. They are used for custom wiring options. Leave them connected together and wrap some insulation tape or heat shrink them to avoid accidental shorts once everything is back in the guitar.
The green wire need to be connected to either your pickup selector switch or to the input lug on your volume pot. This depends on how your guitar is wired.