There are literally zillions of things that can make you a better skiier, and bigger skis can help. The extra edge may be beneficial into keeping you in more control.
The best thing you can do if you want to give your skiing a kick in the ass is join a freestyle team with a well rounded program. It is comperable to lessons, but you can learn to jump and to ski better without the stupid ski instructors who aren't really that good.
If a freestyle team is not an option, start skiing with people that push you to your limits, and mimicing the things they are doing. If they give advice that works for you, take it, and then try and build.
And lastly, just ski. The more you do it, the better you will get. Some off season balance and weight training couldn't hurt either.