I would pick up an Art class at school if possible, or online to learn the basics of design, and then practice a ton. Many people that are good at art is because they have been practicing ever since they were a kid. Drawing all the time. For level design I agree with Nick, start looking into the modding community, Valve has some great downloads for modifying your levels (have only used the left 4 dead one). Any game that allows you to alter the level, or create your own will help. Here is Valve's "Making a Mod"
For programming, Math is pretty important, it makes things a lot easier, and see if your school offers any programming classes as well
Other than that, pick a language/program and try to stick with it for a little while. Learning a certain language won't matter all that much, as soon as you master one Object Oriented language, the others are easy to learn. C#, Java, Actionscript were easy for me.
When you begin learning programming,it probably won't relate to game programming, but stick with it, as these are stepping blocks that are needed down the road.