Simplicity itself. If you get what seem to be nonsense cards, think back to the shuffle - did your mind wander? If your mind was elsewhere and the cards look nonsensical then you know. No problem. Pick up the cards, refocus and reshuffle.
The Tao of Shuffle
It’s not so much about the technique as the attitude and finesse with which you deploy it. So keeping this in mind; begin randomising the cards in your preferred way. I enjoy riffle shuffling because it brings a certain spontaneity and theatre to it. Hold your attention on the question as you shuffle. Not too tight, not too loose. This is important. If you scrunch your mind up with tension, this will also interfere. Instead, feel into the question. In fact; see if you can begin receiving psychic information or impressions about the situation as you shuffle. Not only does that 'calibrate' the cards but often you will receive psychic flashes that are satisfyingly confirmed once you lay out the cards. That’s the visual ‘clicking’ that I mentioned earlier. Even if you do not receive explicit psychic information, the intention to do so is enough to attune the cards to the question. Continue shuffling confidently and when the moment feels right cut the pack and start placing cards. There is a fine line between trying too hard and deftness. Think of the way a potter works clay on the wheel, for example. There is a lightness of touch combined with finesse and confidence. If the potter’s attention waivers or she forces the clay, the spinning pot goes wonky.
A reading is much the same.