waxes are temperature specific, but since you ski park, just get your basic all season wax. make sure to spend the $40 on a ski wax iron as the temperature is more controlled than your moms iron. Youll also need a plastic scrapper and a nylon brush to finish.
I go about 10 times a month or more and I wax them probably 2 or 3 times in that month. Wax em about every week n a half or two weeks. I would do this for both park and all mtn skis. But it all depends on how much you go.