I'm not sure what balls are in your current arsenal. Having that information will help a bit because you may be able to get away with simply changing the surface on some of those balls as opposed to going out and buying new stuff. Still, most bowlers don't go with too much surface. Matte-finished balls at 1000-2000 are usually about as gritty as most good bowlers go because they don't want to blow a hole in the heads. The idea for most of the better teams and bowlers is to stay straight and in one area early to try to create some hook out and some hold in. When done properly, the shot can actually play pretty easy. When not done properly, the shot can be almost impossible because you'll have alternating spots of hook and wiggle. Again though, being a lefty, your situation could be very, very different. I guess my best advice would be to try to bowl on any Sport patterns you can find between now and then. Also, as JustRico said, because there isn't usually much in the way of free recovery at Nationals, it wouldn't be a bad idea to practice going more with the wood. I know that's something that I need to practice every year before going because my house shot is the typical stand left, throw right. Lastly, spares, spares, spares. You're likely to be shooting a lot more spares per game than you're used to, and they're likely to be multi-pin combos as opposed to nothing but single pins. I recommend going straight as much as possible. You'll also probably notice that the ball gets down the lane (even on spares) much quicker than you're used to. As such, be wary of spares like the 2-4 and 2-4-7 because it's really easy to give away the 2-pin with the slicker conditioner they use. Other than that, have fun, and try not to get caught up in the atmosphere. At the end of the day, it's still just bowling!