Start by practicing your balance so that you feel comfortable on the board. The easiest way to do this is to put your skateboard in the grass somewhere and practice getting on and off of the board. Once you're comfortable on the grass, move to the carpet. This will give you a sense for how it feels to be on the board. Then, practice kicking off on a flat, smooth surface, like a tennis court. It's key that you get used to be balancing on the board before you try to do any tricks or head out to the skate park.