The first thing to do is practice the Center Tear (or any sleight or secret action) until you can do it without thinking about doing it. You have to train your muscle memory so the action becomes automatic. If you have to think about doing it, you don't have it down.
Flitting from one method to another, constantly looking for the "best" method, is counter-productive. Settle on one method and make it your own. Later, when a certain level of proficiency is reached, refinement and polishing is possible, but, in essence, stick to one method and perfect it.
Once you can do the move without thinking you must integrate the sleight or secret move into your presentation....again, without having to think about it. A script is valuable here as is the ability to understand the beat/tempo of your presentation. Moves should be done on the off-beat, when people are relaxed and distracted - thinking about something else...looking at something else.
Once that level is reached, you have to re-learn the presentation so that it sounds spontaneous, not rehearsed or done by rote. The currently popular word for this is "Fresh."
At that level are you then ready to present it to the public. Self-confidence comes at this level because you know you can let yourself focus on the minor adjustments necessary when working for an audience. Every audience is different, needing tiny adjustments in your presentation, timing, delivery, etc.
With lots of experience comes the ability to adjust to these needs almost automatically. It takes a long time and lots of attention to detail. It can be difficult, which is why so few attain that level.