<p>Wait, do you mean English as in language skills, or English as in interpreting literature…?</p>
<p>Either way, reading would help a bunch. Pick a book to read (either along with him, or one you already know) and start by going over basic stuff like plot and characters. Have discussions on those two. Then, when you feel like he can comprehend books on a basic level, move onto to harder stuff like symbolism and themes. What is the author saying with their book? What are the author’s opinions on some of the bigger ideas of the world? Make him use textual evidence for his claims, and have discussions with him on alternate interpretations (since it’s possible you’ll see different things).</p>
<p>If it’s just language skills, though, vocab exercises could help.</p>
<p>As for essays and such, leave that to his teachers. You don’t want to take their job completely, do you? ;)</p>