How do you find a vacuum leak 96 tercel?

I have a mechanic buddy who is good at finding vacuum leaks. He takes a high flash point solvent and spray it around on the intake. Near vacuum lines and around the intake mating area. Use the little red tube for accuracy in spraying. Spray a little at a time, with the engine running. You will notice the engine RPM's will come up when it sucks the solvent in the motor. Feeding the motor more fuel that is from the spray can. I'm sure he uses carburetor and/or injector cleaner in the spray can. Brand doesn't matter. Avoid the hot exhaust manifold at all costs. A sucking/hissing noise will be heard on bad vacuum leaks. Wiggling vacuum lines and gently pulling on them will make leaks surface too. If you see cracks, breaks, or severe dryness....Replace these line for best results.