Learn at least one word per day, read articles which are not too difficult nor too easy for you when having time, absorbing financial aid information on education-related blogs, and make sure you understand the materials of your school work (UNDERSTAND is not equal to SCORING HIGH, although when understanding, your scores won't be low). A scholarship you may be interested in is QuestBridge (practice finding it through search, which you must need in college).
Know where you want to go, think about location, school size, programs you're interested in. Research colleges you want to go to. TAKE tours of campuses, this helped me make my decision. Know what their application requires. Take the ACT or SAT depending upon what is requires. Get your recommendation letters in advance, from teachers, advisors or employers, those who know you best. Apply early, the earlier the more money you can get. Apply for AS MANY scholarships as you can while you're still in high school, there are less as you get into college, but there will still be some, and apply for those too when the time comes. It looks good on your college application to have as many extra curricular activities and leadership roles as possible also. Some good places for scholarships is fastweb.com, cappex.com and even just googling scholarships will get you some too. Hope this helps. Good luck!
Get involved in activities in high school! If you're used to having lots of things to do in high school plus school work, time management won't be so difficult when you want to go do a few things around campus (or off campus with your friends) and you have studying to be done. Also, decide what is smart to do and what's not. College is a really good time for experimentation, but if you get too involved with experimenting you may not be able to pass your classes and come back. Don't risk the rest of your college career for one semester of going crazy. It sounds easy, but too many people do it. Another thing that sounds easy but isn't, READ THE BOOK! Your teacher may teach slides and give great notes, but a lot of times what's on the test isn't directly from the notes and they probably won't tell you that. Taking time out to really understand the book lets you really know the material and pass the tests/class. And you may find out that the book's more interesting than it seems.
Start thinking of Majors and maybe careers. What could you see yourself really doing and (at least somewhat) enjoying? The sooner you get an idea, the better. There's probably something you've done before that you were good at and liked doing. Do it a few more times and put those on a resume to remember them by. If you know what you wanna do going into college, 1, you're already ahead of a lot of other students, and 2, you can spend 4 years making connections and learning more about it. Best of luck.
Most high schools do their best to prepare you for college. My school had lots of meetings with the parents and students. They passed out lots of literature about all of the things you are asking about. Yours will probably, too.
Academics - take the most challenging course load in which you can do well; Extracurricular - make sure you're involved in something (in school our outside of it), look at the activities in which you are involved and try take on a leadership role in the coming year; Tests - decide what tests you want to/have to take; Careers - think about what you want to do with yourself after college...then use your family, friends, teachers, etc...to reach out to people who already do those jobs and find out more Search: use sites like this to gather information and see what's available. Visits: make an official visit (register through the admissions office) to 1 or 2 local colleges to see what a campus visit is like, get a taste for what's on a college campus, and figure out what you do or do not like about it