I am by no means an expert but in 2 different shows I have entered locally both had different rules regarding labels and hanging sleeves, so definitely read the information regarding the show you are thinking of entering.
As far as washing, most of my quilts were unwashed except for one which really need blocking (big lesson learned with that one
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Enjoy the experience, it is so nice to see your quilts displayed and even if it doesn't win anything it might just inspire someone else to give something a try or to enter a show too, and we all love eye candy.
I would love to hear any other tips.