Installing numorous electrical devices

[deadend1970]

I am finishing up my project and I am currently in the electrical stage and I have no idea how to wire in all the different electrical devices I have for the car. For example I have two electric bottle openers for the nitrous, two bottle warmers, the cpu for the gear venders over drive, MSD retard, Nitrous timer, etc. How do I connect all of these to a possitive (+) and negitive (-) power supply. Is there a special adapter or do I cut and splice into the keyed hot or constate hot power supply. What about grounding all of these? Any help is greatly appreciated.