While the details of car stereo installation may vary from vehicle to vehicle and among different receiver models, the basics are typically the same.
For your average receiver installation, you'll need these tools as a bare minimum: a mounting kit for your vehicle's make, a wiring harness for your vehicle's model, a wire crimper/stripper, and a screwdriver (Phillips tipped).
You'll also need some way to join bare wires, because our installation is a temporary one, so we're using twist caps, but for a more permanent install, you'll want to solder your connections.
Not pictured here is the wiring harness that will come with your new receiver.