|John Bennett RPG Superstar 2011 Top 8 , Dedicated Voter 2013, Star Voter 2014, Star Voter 2015 aka John Benbo|
I was actually a first timer (and only-timer) when I entered in 2011. Looking back, I would definitely say to not be too discouraged if you don't make it in your first time. Instead, make sure to follow the contest closely (what missteps contestants make with entries, what things they do well) and bone up on your Golarion lore (it tripped me up and I've seen it trip up other contestants). I don't know if I would have done better if I had more experience with the contest but I definitely think it wouldn't have been a bad thing.
But if you do get in your first try, then good luck! I would use the remaining time before the Top 32 are revealed to practice your cartography skills just in case.