Article: The falsetto "register" (though it's more of a muscle placement than a register) lies at the top of your range. It's a different type of voice that can be found by experimenting with high-pitched sirens – that's when you mimic a siren on an "ooh" sound just like a fire engine or a police car. Do them from the top of your register; not to the top of your register. Start as high as can – that should be your falsetto. It doesn't matter if it sounds good, it just has to be a legitimate note. Many voice teachers tell their male students to start talking in their "little boy" voice. Talk like you're three or four years old – can you hear the difference? Can you feel the difference? It should feel more up and back, in the sinuses (or mask) of your face.  If that doesn't work, try imitating a woman's voice. You'll likely take on a breathy, airy tone, vaguely reminiscent of Marilyn Monroe. This is likely your falsetto. It's possible you're going into head voice, which is different. That voice will sound a little stronger and a little more like Minnie Mouse. If this sounds accurate, try finding a register that you can't feel in your throat – many singers speak of feeling a "muscle relief" with falsetto. Unless you're the next Pavarotti, you probably won't be able to produce much sound with falsetto anyway. So when you go to find it, don't push yourself (and definitely don't use your throat). Keep it quiet. You're Marilyn Monroe talking in a hushed voice, not Miley Cyrus screaming at the top of her lungs. You may find that if you try to sing louder, you'll fall into head voice. Does the resonance of your voice change? Do you start to feel it in your body? Then you're not singing in falsetto anymore. " Because of the way the throat and vocal folds are constructed, "aaa" and "aayyy" do not work well for finding falsetto. "Eee" and "oooh" are much more conducive to getting the sound up and into your mask and letting your vocal folds go. On this vowel, slide around from top to bottom. Do you hear how the timbre of your voice changes? When it gets really light towards the top and you feel fewer vibrations internally, that's your falsetto.

What is a summary?
Do sirens from the top of your register. Go into your little boy voice. Keep it quiet. Sing on "eee" or "oooh.