Arduino wire question
Personally I like to try to use red wires for +5V, black or blue for ground, and yellow for data. However as Majenko said in a comment, the colour is irrelevant to the operation.

The usefulness of colour is just that if you stick to a system (like red for +5V and black for ground) then there is a visual check you make when connecting up a circuit, so you don't accidentally put things in backwards, like you might if every wire is yellow.

Also, if you run half-a-dozen wires from one place to another, using different colours is another way of making it easier to see you have connected the correct things together.

Having said all that, the colour does not otherwise affect things.