I am not sure what is meant by lacing. Is it when I sort of let the cards fall into one another without adding thumb pressure, so they make various layers from left to right, without so much bending? Whatever that is, I do that at times. I also sometimes section the cards into smaller decks and rearrange them. I sometimes take out random cards and put them into random sections of the deck- just slip them in, but care must be taken not to harm them that way. I will also take random sections out and place them somewhere else. But I always spread them around because I do reversal readings, and to me this is a reliable way to allow me to make sure some cards are flipped upside down and not others. If I regularly just flipped entire deck sections upside down, I'd prob. end up with entire readings in reverse or rightside up. When I am spreading them about I sometimes take clumps of the spread and place them over one another or gently slide them together, so the cards interlock.
I do NOT riffle. Ack. I do that with playing cards, but not tarot cards. It causes too much damage. I would never want anyone to do my cards that way. I explain to people beforehand how to shuffle. Indicating I think it's a good idea to spread them so some stand upside down, and that otherwise to mix them until it feels right. I need to be very clear, though I think, and explain- do not riffle. I've had people take sections out and rearrange them I think, but do not recall any rifflers. I like the idea Dimwem gave involving tossing them in a bag. Never tried that. Interesting.