There's no such thing as B2. You mean A2 or B3 isit?
For English, I would agree with TheSoyaz. Read more English
Newspapers and follow-up with the current news.
For Paper 1, You can buy editing exercise books. Editing is 10
marks, try to get full marks. Even if you get only a 8, it will
pull up ur score quite alot.
And for ur compo, GGliaooo has a good point. But for me I did
narrative and its actually do-able coz i was writing about myself.
When u write about yourself ur compo of course will be full of
emotions 
For Paper 2, its really practice. But for the summary when they
tell you to take points from, lets say, line 15 to line 42, then
make sure you get your info from there
only. One foolproof way is to draw a very obvious
line at line 15 and another line at line 42. liddat u confirm can
see where to get ur points from.
If you don't know what to change the key words to, I rather you
don't change. You see ah, Summary total 15 marks (i think... I took
the paper last yr, forgot liao) 8 marks for content, 7 marks for ur
language. If u try to change ur keywords and changed it into a
different meaning, you will lose both content marks and
language marks. I rather you copy paste the exact same
word and get only the content marks than to lose both.