How can I raise my (8th grade) ACT score from a 23 to a 30+ by the time I'm a senior?

Answered

So first, make sure you understand that taking exams like the ACT or SAT in 8th grade means that—naturally, by where you are in school—you have not learned all the content that's on them yet. Particularly in the math and science sections, but even for reading and writing, the ACT and SAT are geared for the level of knowledge that high school juniors (and some advanced sophomores) should have. Your score would almost definitely improve naturally from a 23 without any prep on your part, so hopefully that makes that rise seem less daunting.

In terms of prep—which I would start maybe towards the end of your sophomore year, once you've learned most (or maybe all) of the material that will be on the ACT—the best thing to do would be to begin taking practice tests. You can pair those practice tests with a study book like the ones that come from Princeton Review or similar companies to help you, or go through free prep courses available on the internet. Khan Academy has good prep for the SAT but doesn't offer anything for the ACT; still, if you're set on the ACT, there should be similar resources available that you could find with a quick search when the time comes.