In 12 years, it is not hard to prepare enough to do well on the SAT/ACT. They don't even cover calculus. Get that out of the way in a few hours, then spend the rest of the time on more interesting things.
Getting into a good college isn't about testing--good testing is a necessary condition, not a sufficient one. You need to show that you are going to contribute to the community. You need to have lots of extracurriculars and serious leadership in some of them--and ideally in some volunteer group not connected to the school. Serious leadership and success in one is more impressive than having fifty groups with no leadership or success, but the basic idea is if the kid is curious and really applies himself at everything he does, he has a really great chance of getting in to a good school.
That includes grades and test scores, but they're not enough.
And better, if a kid does that then they learn *how*, and that gives them a richer life going forward.