i started out siing when i was little, switched to boarding in 5th grade and did that up until last season when i switched over....
As for park, i'm already better than i was boarding.....i would say just set some goals for the season (i got up to grabbed 5's and basic rail stuff) but really get used to what you are doing. The first few days were really weird siing but i got used to it.
And get out of the park a little. MY friends too me in the woods and i didn't now what the hell i was doing
Try to ski with some skiers who are better than you. It will help you progress faster and they can push you a bit when you want to learn something new. I tend to be scared pretty fast trying new things but with some other skiers you just go for it and most of the times works out pretty well. For some basic trick tips check the trick tip cults and http://www.skifilm.com/blog.php
And most of all have fun!
do not, NOT focus on just park skiing, learn to really ski before hitting the park. when a powder day comes around and you have no idea what to do besides bomb it to the park you will look like an idiot. Have fun and good luck