Check out the various organizations on the internet and look at their photos to see what category is best suited for you.

Attend a competition as a spectator first, so you know what to expect and what the judges of that organization are looking for.  

Start compiling a checklist of items to pack for your show and pack in advance so you don't forget anything.

If you're doing your own make-up, do it before you arrive to the venue.  This will give you more prep time for pumping up and make you feel less rushed backstage.  You may only have to touch up if necessary.

Strings on your suit should be pulled tight to fit the body snugly.  The suit should move with you, not independent of you!

Smile and look like you're having fun the entire time you're on stage, it will capture the judges attention and help you to relax and really have a good stage experience.

Take notes after your experience to determine what you learned from the show (what to do and more importantly, what not to do for next time).