wiring amp to stock headunit

i am wanting to wire a amp up to a stock head unit, and just wondered how i would run a remote turn on? i have done this b4 but cannot remember how i did it. and then for the sub do i splice into the rear deck speakers for my speaker wire? if someone could help itwould be greatly appreciated.

If you let us know what kind of car you are installing this in, it would be much easier for us to help you.  As far as the remote wire, most factory radios do not have a suitable output wire to turn an amp on.  In most cars we would connect the amp remote wire to the switched wire on the radio.  Only problem is that the amp will turn on anytime the key is turned on.  I would reccomend that you use a line out converter to obtain signal.  You really should connect it behind the radio. 

i usually tap on to the fusebox, anythingthat turns on with the ignition like windshield wipersIf I'm to loud, then you're too old!!!