What would you say are the most essential ways to improve English for High School for both getting a good grade/score on the SAT as well as legitimately improving English skills? My nephew is going to be a freshman and his English isn't the best, so I want to help him improve that so he won't struggle in classes or in the SAT. Say I have once a week to help him with his schoolwork, and I'd deal with SAT when it gets near. Hopefully his English skills would be adequate when the time comes for SAT and he can prepare well on his own.
For example, I do not find putting a lot of time into studying grammar worthwhile because grammar is just a set of rules that can be memorized or naturally picked up along the way, which does not require as much work as other aspects of English. SAT grammar is easily memorized and thus does not require a bulk of time (years of study prior to the test) to do well.
Regardless, what do you think are the most important methods to improve English that would naturally help future SAT preparation?