Different people work differently. I work under extreme pressure
and on a interest base. My aim was to study IT, so I make sure I
did well enough for the O Levels. Not just the bare minimum.
For English, it's a lot of reading and practising. Newspapers,
non-fiction books, fiction books, comics, anything. But do read a
variety. Non-fiction books don't have fancy words like what a
fiction and comic book has.
And if you are slightly lazy, go Google and just type in define:
the word you want to know, and you got the definition. See how it's
being applied in different context.
You are lucky not to be retained even though you failed English.
But O Levels is another thing.... a D7 would automatically
disqualify you from polys, JCs and perhaps ITE. Unless you are
talented... on a case by case basis then you can get in...