Well when ever I go to a show I always like to do a few things to make my birds look there best
-Trim there nails. I find using a file at the end gives the nails more of a smooth, natural look.
-Look over for broken/discolored feathers. Pluck these out.
-Wash the feet and face and gently wipe down the feathers with a damp towel. This makes the bird pop more. If you plan on actually washing your bird, make sure you do it at least 5 days before the show. This give the animal time to get back the natural oils that have been washed out.
-You can use baby oil and rub down the legs and wattles/comb. This makes them softer and brings out the color on there face. make sure NOT to get and baby oil on the feathers. It will ruin them
-Keep your bird in a nice, clean cage. Change the bedding's at least once a day, if not more, so that the bird wont get any mess on them
-Work with your bird, make sure she is calm towards people, especially since they will most likely be picked up and handled. Simulate what a judge would do; spreading the wings, checking the nails, looking over the feathers, looking over the face etc. etc.
-And one of the most important things, HAVE FUN!