Lacking a meeting to attend, the best advice I can give a first time orchid show exhibitor is to take the following 10 steps to simply make your plant "prom worthy, so to speak.
1) Choose one or more of your plants with flowers free from damage, ie no slug, snail or physical problems.
2) Attractively stake the flowers and clip the top of the stake off so it does not detract from the flower. Staking should be done early before the buds open and preferably they should not be looking up at the ceiling. (Browse the internet for similar genera and see samples) Judges do not like to stand on their heads to look at flowers so always try to "make the flower stare at them directly".
3) Clean the old bracts off the stems/pseudobulbs and remove any old flower stems. As I grow cyms, I also cut off at a sharp angle any dead tips of the leaves.
4) Wipe both sides of the leaves with a wet paper towel. Some people use a 50/50 solution of water and non fat mild or a dilute solution of lemon juice. Both are slightly acidic and will help remove any water stains.
5) Top off the top of the pot with fresh mix if necessary.
6) Find the full name of your plant ie cross, cultivar and parents if it is a hybrid. The RHS website will give you this info. As a beginner, you can probably enter your show with a NOID and if it is a Catt, for instance, it should be entered as Catt. hyb ign 'cultivar name of your choice'.
7) It is not necessary to put the plant in a fancy cache pot (decorative pot). Although often very pretty, it can detract from the flower.
8) Place the plant in a box well braced for travel to arrive safely at your destination.
9) When you arrive at the show, you will need to fill out a card with the information from #6. The people entering plants will guide you as to what class the plant(s) will be entered in.
10) Enjoy the experience, take lots of photos (be sure to also take a photo of the name of the plant photographed!) and have fun talking to other club members and fellow exhibitors. In other words, HAVE FUN!
Good luck!