more specs on system.

my guesses......
1.(assuming you have amps)use BIG ground wires and keep them short! 8guage min from the amp, 4 if allowed, or what i do, 8guage from the amps to a dist block, then 4 guage to the nearest point of ground.
2. always run cables with like cables in car. you have 2 options:
first, run rcas and speaker leads on side oposite battery, and then run power wire and amp turn on on side of car that the battery is on.
second, *best* RCAs down the middle of car(requres moving carpet/seats) speaker leads on side a, power on side b. worst case, you can run speaker wires from amp to power side speakers on that side, but avoid if possible.

next, RCA's are KEY! expect to spend atleast (Very Cheap)$20 each rca cable. Mine were around $120 for each RCA cable but they really do make a difference. A lot of times, you can bargain with audio shops for wiring and RCAs when you buy a head unit/amps. They have markup in cases like that to cover installs and wiring. As to the ground wire, just buy some wire at radioshack for that. expect $1/foot or so....2+ for thicker wire.

Last. Run good speaker wire that is 12 guage or better.


Hope that helps!