Ensuring your robot is wired correctly is incredibly important. If wired incorrectly, your kit may not work correctly, or may be damaged.
Ground should be black, and nothing else should be black. This is in the interest of both safety and organisation. Being able to see where all your ground cables go allows you to easily track cable runs and diagnose electronic issues. It also greatly reduces the chance of incorrectly connecting any power cables to ground, which would short-circuit the battery and seriously damage the kit!
Keep your solder joints clean
Sometimes, you'll need to build your own circuits to extend our kit, which likely requires soldering. Keep an eye on your solder joints so they don't create a bridge between components. This will likely lead to the electronics not working correctly.
Use higher gauge wire
If a component is likely to draw a lot of current, it's best to give it a thicker wire. The motor board is likely to draw the most current, and so should use a very thick wire (like what is in your kit). Trying to draw too much current through too thin a wire may cause your kit to stop working or potentially set light. Using thinner wire will be fine for small, low-power electronics, such as microswitches.