Wanna be a card sharp? There are a lot of things you can do to make yourself look impressive, but the first, most basic thing is shuffling, or mixing the cards. The shuffle in this instructable is the riffle shuffle. Please practice lots before showing off, to avoid embarrassment.
Step 1: How to Hold the Deck
First, hold the deck with your thumb on one of the short ends, your pinky, ring, and middle finger on the other short end, and your index finger curled in the middle so that the knuckle is pushing down on it. Hold the deck in your right hand. (Note: If you are left handed, please reverse all hands throughout this instructable. For example, here you would hold it in your left hand.)
Step 2: Split the Deck
Now you're going to split the deck approximately in half. Do this by applying pressure with your thumb and pinky-middle fingers while pushing down with your index finger to bend the deck. Now "riffle" the cards off of your thumb by moving it up the deck. The cards will individually go straight when they come off the tip of your thumb. Stop about halfway up the deck.
Step 3: Split(Cont.)
Now put your left hand into the split, to make two separate piles of about the same size. Hold the second deck like a mirror image of the first.
Step 4: Bend and Shuffle
Now bend both small decks like in step two, hold them within about an inch and a half of each other, and riffle both at the same time so that they overlap every few cards, all the way through. You may have to experiment with the length.
Step 5: Waterfall
This part is just for showing off. If you want, you can just push the remaining cards together and square the deck. (Square the deck=push all the cards together so that they are all together.) If you did it right, you should now have to loosely interlocked decks of cards. Your pinky, ring, and middle fingers of both hands are underneath the deck on both sides. Your thumbs and index fingers of both hands are hovering, awaiting further instruction.
Step 6: Bend and Waterfall
Now, with your last 3 fingers in the same place, bend the entire thing in the middle, so it's a half circle. Put your thumbs on top to keep the cards from launching all over the room. Put your index fingers on the bottom, too. To waterfall it, slowly release the pressure, moving your hands slightly apart. Square the deck.