Choose the type of cable and connector that are appropriate for your audio situation. Balanced cables offer more protection from interference and audio noise, and are generally used for recording and other precision audio applications. Unbalanced cables, on the other hand, are cheaper to buy and make, and are more frequently used for live audio situations, because they are more vulnerable to electrical interference than balanced cables are.
Cut the appropriate length of audio cable from your bulk audio cable reel. It is a good idea to cut at least 6 inches more cable than the situation calls for, to allow for length of cable lost during stripping and application of the audio connector. Make sure you cut the cables in a flat and even way to allow for easier soldering.
Apply the instrument cable connectors to the ends of the unstripped audio cables to determine how much of the sheath of the cable needs to be stripped off before soldering your audio connectors to your instrument cables.
Using a cable stripper, or, lacking that, a very dull, somewhat serrated knife, strip the sheath from the appropriate portion of the audio cable. Do not use a very sharp knife; it may cut the cable instead of the sheath, and it can also easily cut hands. A dull knife is better for removing wire sheath if you do not have a wire stripper.
Using a hot soldering iron, warm one of the wire connections at one end of the stripped cable. Do not melt the wire. The warm wire will help make a better connection with the connector when the solder is applied.
Carefully warm, then solder the appropriate wires in the connector to the warmed wires of the cable, one at a time. After you have finished one connector end, move on to the connections in the other side of the cable. Allow both sides to cool
Wrap any exposed cable that remains after you have soldered the connector in electrical tape to protect it from damage and exposure to the environment.