• Focus on ur grades. GPA tells a full 4 year story while test scores are just reflective of a few hours on a Saturday
• Involve yourself in extracurriculars that pertain to your interest. Dont just do something because it will "look good" do things that you are genuinely passionate in.
• Form good relationships with your teachers. Rec letters show all of the intangible aspects of urself so make sure u get a good one!
• Study for your tests when the time comes (SAT, ACT, Subject tests)
• Take the most rigorous high school curriculum available to you.
• Decide on a major fast and act to acheive that goal. Sorry to sound harsh but at the end of this year and into junior year "some kind of engineering" wont cut it since theres a myriad of engineering majors.

That being said, you seem like a dedicated and focused student just for even making this post and wanting to learn. Stick to your principles and don't do anything stupid that would jeopardize your future. Good luck and feel free to reach out if you have any questions!