My Grandpa showed me how to 'fancy' shuffle cards when I was 4 years old. My parents helped me practice until at age 5, I finally mastered it. (Thanks Pops) My favorite thing about investing that time is that, like riding a bike, my muscles never forget how to do the fancy shuffle no matter how long I go without touching cards.
For the pure satisfaction of looking like you know what you're doing when you sit down to play any card game (read: How To Look Like a Card Shark), I highly suggest taking the time to learn. You won't be sorry! And don't worry, you won't take as long as I did to learn. I blame it on the tiny hands... : )
NOTE: Card selection plays a huge role in how easy or hard this type of shuffling can be. If your cards are really sticky or too slippery, shuffling will be harder. I recommend getting either Hoyle or Bicycle brand cards.
Step 1: Practice Makes Fancy
Before you dive in to learning the nuts and bolts of fancy, or 'bridge', shuffling, take a few minutes to practice what's called 'rifling'. This means letting the cards cascade down one at a time towards the table (or your hand), controlling the speed and flow with your thumb, which sits on the top edges of the cards. (like pictured)
To get started, true up (aka straighten up) your stack by holding the deck between your thumb and middle+ring fingers (the front card of your stack will snug up right behind the pads of your middle & ring), while clamping down on the top with your index finger. Bang the stack against the table a few times to get them aligned.
Holding cards for successful rifling is exactly the same finger placement as above, with one exception: Take your index finger off of the top (long) side of the deck and bend it in, placing it on the middle back of the deck.
Now pull back and slide along the top of the cards with your thumb as you push in with the back of your index finger, releasing the top of the cards down one at a time in a 'cascade'. The pads of your 3rd & 4th fingers will 'just' curl around the bottom of the deck and hold onto the cards so they don't go flying.
Doing this without dropping the cards in clumps takes practice, so don't be discouraged if the cards aren't delicately 'cascading' right away.
Practice this with both hands until you get a feel for it.
*Sometimes the cards get a little bent from the pressure of the bend. Not to worry! Stack them all together again and just bend them in the opposite direction. They will straighten out without creasing your cards.