So I had to use this on my wife's old car but I am seeing more and more issues people are having with leaks being posted so I figured I would throw my solution out there.

If you have that intermittent overnight drip there were two things I've used to locate it's exact location:
First one is best if you do not own a garage: Sideway chalk. Park, line up your bumpers and sides. I usually put a notch in for the door locations or wheel wells for some point of reference so when you're under the car next you know roughly where you are.
Second is best if you have no clue what is leaking or if it's leaking: You can usually locate long paper rolls (36" x 200ft) either at Home Depot, OfficeMax, or even a local Kinkos may sell it to you. Roll it out under your car and you will be able to identify what and where it's coming from.

For me it was helpful with an oil leak, which I determined was coming from the crank seal, which lead to a new car.