Best ways to up a score?

What have you found to be the best ways to up an act score? I want to up mine by at least six and I’m not sure what is the most effective way to do this. For those who have upped their scores dramatically, I’m calling on you for help!
Is it best to study hard on your own, go to prep class, get a tutor, just keep taking the test, etc…
I really need scholarship money, so all help is appreciated!

@mayplesyrupmoose , The folks that I know that have had the most success have hired tutors who have demonstrated success in improving scores (and who have cost a boatload of money), and they’ve used them for about a year. (!!!) I’m guessing that the reason they work well is that it’s impossible to slack off one on one, they can figure out what you (rather than the class) need to know, and they know what can be taught and what can’t so the focus is effective. So with that said, I suspect that if you’re diligent, you can probably make quite a bit of progress on your own with a good book IF you’re good at figuring out what you need to improve. I can definitely see a tutor helping with math – if you don’t know how to do a certain kind of problem, the tutor can teach you. Vocabulary you have to memorize, so someone else isn’t going to make a big difference. You can probably get good strategies for some of the other parts from books and online.

If it were me at this point, I’d probably take a class over the summer. It wouldn’t be on top of school work so I could focus, and there’d be some structure. I’d have time to study on my own. I know that often the teachers are happy to answer specific questions and provide personal help (i.e., what you’d get from a tutor), but you’d have to be on top of things enough to know what to ask. Really, a lot of it is about your motivation and ability to work on your own. I’d say that if you still needed help after a class, you could consider a tutor for that focus.