I just use quick, precise motions, similar to what one might use when opening a thumb-flip pocket knife or opening and lighting a Zippo lighter. Little flicks here and there that make cool-sounding noises and get the job done efficiently.
A move-by-move breakdown of what I do to open a pack. Bear in mind I'm a lefty, usually using the mechanic's grip in my right hand.
- Grasp pack in right hand, thumb cutout facing up and left.
- Place left thumb on lid at thumb cutout, apply pressure and flick open with a downward motion.
- Use left fingers to push lid back - if the lid is new, creasing back the lid hinge on the face - and grasp the entire deck.
- Place box down, place deck in right hand into a face-up mechanic's grip, face up.
- Count off of the deck, one at a time, the extra cards (ads, jokers, gaffs, etc.) into the left hand and flip them face-down as a group between the index finger and thumb.
- Regrip the extras between thumb and middle finger, with index finger pressed against left edge.
- Turning the right hand face-down, still holding the deck in mechanic's grip, pick up the empty tuck box between thumb and both the middle and ring fingers.
- Line up the bottom edge of the extra cards at the tuck opening, between the lid and the flap closest to you. Flick it into the box with a swift move of the left index finger.
I usually leave the box open, ready to slip the cards back in or remove one or two of the extras at a moment's notice. That probably reads a lot more boring than it looks...
I'll sometimes use two identical jokers for an exchange where I make the spectator believe he's holding his card when in the end he's holding mine. Now some people conclude, "oh, but a deck has two jokers," so what I do is use a standard pack of Bicycles and an extra guarantee joker from another pack, leaving me with five extras instead of four. I use the guarantee jokers - which most people wouldn't expect doubles of anyway - for the exchange, pulling them out together as if it was a double lift and present the remaining extras if necessary after the trick to convince the spectator that I didn't simply "use the other joker". Works pretty well.