Plugs are a great way to make components easy to connect and disconnect. This can save a lot of time when assembling robots because it reduces work of undoing permanent connections in order to modify some parto of your project.
Here is a quick tip for robotics and electronics projects when using plugs.
Always connect the female plug (one with receptacles for the pins) to the battery side of the connection.
If you follow this method you help to prevent a short circuit if your connection ever comes unplugged. You also help to reduce the risk of electrocution if you are working high voltages.