Are you nervous when performing every effect in a routine? From personal experience, I tend to get nervous and get shaky hands during the first effect, but after that, I'm fine for the rest of the effects. If you are performing for a person or group you have never performed for, you don't know what reactions to expect from them. After that first effect, you now know what they think of you and your magic, for the most part. If there is a positive response, run with it. Hopefully you gain for confidence for the rest of the effects. Also, you've broken the ice after that first one, so the audience should be a little more relaxed. Secondly, you may are nervous because you are thinking your sleight of hand may not be great and you are afraid of messing up. If you know you have practiced the sleight hundreds or even thousands of times, when performing, just perform the move as clean as possible. If you mess up a sleight early on, by the end of the effect, the audience will most of the time forget about it because they are reacting to the "punchline" of the trick. The audience response at the end of the effect will sometimes provide you with information on whether or not your mess up was significant. Just try and feed off of the audience and gain confidence in the moment.