Before getting to the more mechanical needs in preparing for a computer science journey, the advice I start with...it will be important for you to understand for yourself, what your level of tenacity, determination and dedication is. May sound heavy for a high school student :) but a journey in computer science can be like any other journey. Some parts are harder than others. Some parts are easier. The key is how you respond during difficulties. Understanding this about yourself is particularly important because there is a lot to learn in this space AND there is always something new coming into this space AND as technology changes "old stuff" gets removed or downgraded in this space.
So in short, your desire to trouble shoot and problem solve, will be a key driver to your overall success in that field. Beyond that, there are the mechanics of what you will learn. Math (calculus), physics, statistics are a few of the broad based curriculums that you will face. Openness to coding languages is another big plus...and may be the best place for you to discover how much you want to learn in this space.
Working well with others..again may sound a little corny :)...but your ability to collaborate with others, that includes sharing information, is another huge part of being successful in this space.
I hope you find this advice helpful. Best of luck!
Don't worry about a lack of formal CS education now. There will be plenty of students just starting out in computer science. But do take it seriously: find something that you enjoy (e.g., games, sports, apps) and learn on your own how to make those yourself. And don't skimp on math. There's an old adage that an ounce of math is worth a pound of programming.
Pick a college with a bunch of schools _i.e. school of business, school of engineering, etc .... In the event you don't like computer science, you can stay at the same school and transfer around.
Bond with the conselors there. There's no sense in not using their expertise.
Knock out the prerequisite courses first .. there's usually a math, science, and english, and if you can dabble in computer science the first year, then you're set.
Worst case, you can always start with computer engineering, then step 'back' into computer science (or another computing discipline).
Focus on math and logic for now to get good basis.
Consider installing Linux on some machine and playing around with the command line some, just to have familiarity, because it'll save you time down the road in computer lab (so you can focus on learning actual CS stuff, instead of the ever common "why doesn't this work on my Unix box" that'll happen in lab and detract from the real lessons).
If you have a lot of free time, consider looking at Learn Python the Hard Way (but don't sweat it if it doesn't make a lot of sense yet).