some great advice. I took a class from an award winner on "big" show quilting--she said the binding is the first thing judges look at--is it even both front and back and "filled--she used a glue stick & her ruler to attach before sewing. Ditto on sewing down the corners (front & back).I would add that you also need to remember that even if you do an excellent quilt, the judge(s) may be partial to a different style (our county fair judge basically told me she hates modern quilts--well dang!) or the competition may be amazing. I know several people that enter quilts into big shows and they say a quilt may not do well at one show, but another show it may win.
I'd add that one of the trick I learned from the award winner is to make rounded corners if you are not excellent with mitered corners!