I'm about to tell you to do something senseless.
Perhaps I should say “sense-less” instead of senseless.
What is sense-less practice? It is a way of improving your skills by the absence of one of your senses.
For example, you are practicing your second deal. Normally, you either watch the deal from your point of view or the view from a mirror or video camera. This takes you out of the moment. You aren't truly present with the sleight when you are observing it.
How to address this? Simple. Close your eyes. Yes, closed. No peeking. Use a blindfold if necessary. Now practice. Feel the cards. Feel their form in your hands. Do the sleight. Feel how your hands move. Most likely, it will feel horrible. Awkward. Uncomfortable. Push through that fear and practice without sight. As progress is made, your other senses (in this case, touch) will become more sensitive.
When you feel that you have made progress, do it again, but this time, in front of a video camera. Watch the recording. See where the move lacks, then practice it sightless again. Do this until you can do the sleight effortlessly without sight. This is the path to mastery.
Experiment with the absence of other senses. Wear ear plugs so you can't hear the cards moving in your hands. Wear gloves (start with form-fitting latex, progress to cotton for the courageous) so you can't feel the cards. This is like a runner wearing ankle weights. The weights make the athlete work harder. Practicing with gloves on will be challenging as hell. But when the they come off, the transformation feels amazing.
If you pursue this technique seriously, you will become “one” with the move. You won't just master the sleight, you will be a master of it.
Enough reading. Get to work.