Its pretty hard to mess up. You'll develop your own technique after the first time. Personally I like to open the cap on the master cylinder and put a small container under there, then when I use my huge c clamp to drive the piston back in its bore, the spilled fluid is neatly contained. Remember to break in your brake pads properly, have the rotors turned, and torque the lug nuts back on to spec, no as tight as you can!
edit: here is my favorite break in method, give credit to a dempsey bowling
Once installed, your new brakes will need to be broken in. The reason is to set the polymer that binds the brake material together. You will want to bring the car to 60MPH, then apply the brakes hard enough that an empty coffee mug on the seat will tumble to the floor. Bring the vehicle down to about 30MPH, then gently accelerate (using only 1/3 to 1/2 throttle) back up to 60MPH. Again apply the brakes as described. Repeat this procedure 25 times, then park the vehicle for at least one hour to allow the brakes to cool. Be sure to roll the car forward a couple of inches every minute for the first 15 minutes of cooldown to ensure the rotors don't get hot spots on them. After the cooldown is completed, repeat the slowdown procedure five more times and your brakes will be ready for use