12 volt accessory wiring

[Mp5speed]

I was just searching for tips on installing 12 volt accessories that dont have the cigarette lighter plug in. How excactly are you supposed to hook up these wires to the fuse box? And how do you know which empty space in the fuse box you are supposed to hook it up to? And would hooking up too many accessories (along with a power suckin amp w/o a capacitor) drain my protege? My headlights already dim when the bass hits in my car. Any tips would be greatly appreciated. Thnx guyz.