It's hard to be specific, but in general you have to figure out how to set yourself apart from the others (hopefully above them!). And the best approach, rather than looking for a trick of some kind to impress folks, is to 1) play the technique really cleanly, and 2) to actually observe the music's performance markings. My comments assume you have already worked out the notes, etc.
For any technical passage, each day you should play it at half speed a couple times. As you do, strive to make it absolutely clean and even. Pay attention to how your fingers feel as they do this. If you feel awkwardness over a few notes, those will probably sound bad at a faster tempo and may need extra attention. But even if you don't uncover weaknesses, the slow-speed stuff will help you sound more professional when you play at normal speed. Once you have done the passages at half speed, then just jump right back to normal speed. (This is a very time-efficient practice technique that I learned from a famous New York clarinet teacher about 30 years ago and I have used it ever since.)
I assume your sheet music has dynamics, tempo, and articulation marks, and possible some "feel" marks like
espressivo. Do them! And make them work to make the piece as musical as possible. It should be a reflection of your "musical soul" to tell the judges what's inside you. Before you practice, try a measure of each different dynamic in the piece and see if they are correct relative to each other. Is your
p really noticeably softer than your
mf, and is your
f or
ff much louder than your
mf? Once you are satisfied that the various are correct, make sure you keep a sense of that while playing. Is there a difference between notes marked with a dot over them vs. a non-marked note vs. a note with a legato over it? Do the accented notes stand out a bit? And so on.
Mostly learn to enjoy the music within the piece! THAT will make you play better and will help sustain you when you are nervous.
Here is a little more extensive discussion:
http://www.dwerden.com/forum/entry.p...-Advice-Part-2