If you are ready to move up because you have been doing well and both you and the horse are capable to. And are training @ a higher level @ home. Nothing should change if you are just progressing in difficulty. The old saying " If it aint broke don't fix it"
But if you are changeing from local events to proper rated shows, you must change accordingly. Spit polish shine on everything, not a hair out of place, the proper equipment and a serious [ but always fun] attitude.
Watch someone you respect, other than your trainer, and see how they do it. You can always learn by watching, but remember theres just as much wrong/negative as good/positive.