The connection between the sound source and the mixing and output stages is another vital link in the chain. Cables need to be robust and reliably made, with firm and clean connections in the plugs and sockets. If the mixing desk is located away from the stage, it's worth considering a mutlicore reel of cable, which avoids having multiple lengths of wire snaking all over the stage and through the auditorium. A typical multicore may have 16 connections from stage to mixer, with four carrying the mixed signal back to the monitors on the stage. Connection is usually via XLR sockets. For more details on cabling, see our Online Guide to Cables Leads and Connectors.
It's worth investing in good quality cabling. It's the link in the chain that is most likely to get kicked, pulled or trodden on, and cheap cabling may not be properly shielded, which may lead to interference or a poor signal. It also makes sense to have more cable than you think you might need, leaving you capacity for adding other instruments to the mix from time to time, or simply giving you a spare connection in case another fails. And you should make sure that the cable is long enough to accommodate all the spaces in which it might be used.