Depends where the wire is running to and from mate! :suave:
In case of power/ wires from the engine bay which has exposure to heat; :uhoh:
use plastic conduit a bit larger then the power cable all the way in side the engine bay, and secure with cable ties; use correct lug connections and ensure the connections are secure;
In case of behind the head unit, speaker wires, and amplifier wires; :furious:
ensure you apply solder, followed by heat shrink over to avoid short circuits; behind radio and to speaker terminals; use at least 14 - 16 gauge wire for installations;
use cable ties to tidy up wires behind the head unit so that wires and RCA's are all neat and secure;
ensure you use correct size power / ground distribution blocks from the battery to the amplifier(s);
ensure that all connections are safe during installation and no frayed wire is touching the other terminal;
check correct speaker / subwoofer connection to the speakers and the subwoofer input terminals;
check subwoofer input terminal to confirm strong connection;
secure your subwoofer box in the trunk area so that it does not move and hit your amplifier which could cause wires / ground to loosen;
remember, power travels from negative to positive, hence the 12v negative ground theory so make sure you have good grounding point;
Hope some of this suggestions are helpful in your case. :suave:
In my last 2 vehicles, the decks both had wiring issues. They would be fine for about a year, then randomly play on either the left side or right side. Only after about an hour or so would both left and right sides of the car play together. Maybe I should have labeled this as a deck wiring issue?