Definately learn what it takes to psych yourself out so that you can make yourself go before that happens. As far as learning to jump goes, the friendliest way (in my opinion) is on a classic mogul jump because you don't have to worry about having to clear a table (you can go as big or small as you want). Learning in a terrain park is fine but when I was learning I always freaked out about not going too big but still going big enough to clear the table. If you're doing it in the park, get out there first thing and inspect all the jumps, slide up the transition to the lip to get a feel for the speed and check the size of the table. Realize that it will hurt more to undershoot and land on the table than it will to go big and crash. If you go out early, you will have time to check it out and then get some jumps in before everyone gets there. Also, the snow and speed will be very consistent in the morning. But yeah, ideally you'd go find a place in the woods on a powder day and just have fun with it. Having someone with you who at least kind of knows what they are doing will help, too.
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD