Remove the jokers from the deck first (unless for whatever reason you need them shuffled in).
You should use your three middle fingers to hold the deck (i.e. not the pinky or thumb). Your ring and index fingers will be on opposite sides of the deck, putting pressure on the long sides, about halfway down. While your index and ring fingers are doing the actual holding, your middle finger basically rests against the top edge of the deck to provide stability and keep the cards even. For ease, you can also rest your thumb against the opposite side as the middle finger, but it is not necessary. Besides, you'll be moving your thumb in the next step.
Throughout this guide, remember when I say pressure, I don't mean to squeeze the cards, just hold them (like how one would hold a pencil when relaxed).