Well I guess it really depends. As far as rails and boxes go logical first trick would be a simple 50-50 (jumping onto the rail or box and pointing your nose straight downhill). As far as kickers go the first spin you'd learn to do would be a Frontside 180*, and the first grabs you could learn to do would probably be a melon grab(grabbing onto the heel side edge of your board with your front hand), an indy grab(grabbing the toe edge of your board with your back hand), or a mute grab (grabbing the toe edge of the board with your front hand. You can also learn to tail butter(simply riding down the hill lifting the front of your board up enough so that your front binding comes up off the snow and see how long you can hold it for). It really depends on what you want to progress on as far as rails/jibbing, jumping, or simply just freestyle riding around the park.
As your first time riding you should really concentrate on the basics of snowboarding. Learning to stop properly. Learning to get onto your heel edge and toe edges to turn different directions correctly. Finally you should learn to chain your turns together and transition from your heel and toe edge so that you can carve. I know it's hard to keep your focus, but if you learn proper riding technique before you start trying simple park tricks, you'll be much better off in the long run. Also get ready to fall a lot, always keep your arms tucked in, and your head up and away from the ground!
I saw a good video but can't find it now about how to fall correctly (as silly as that might sound). Basically you want to try to avoid falling on your wrists with your palms flat at all costs. If you're falling backwards, you want to keep your arms in and your head tucked with your chin to your chest. This will prevent breaking a wrist, or hitting your head against the ground. If you're falling forward try to go down on your knees first, fall down with your arms crossed in front of you.
Good luck, and if you keep at it, you'll be in the park before you know it.
Last edited by digZ; 01-26-2012 at 12:54 AM.