^At above, you should really know how it works before you say stuff like that. Of the 41000+ students that did English last year, only 5% D+ or lower. That's just over 2000. You're making it sound a lot more than it is.
Looking at it from a totally statistical point of view, the grade distribution shows that a B / B+ average would place you anywhere from 60-70%? Depends if you're a high B+ or a low B average.
http://www.vcaa.vic.edu.au/vce/statistics/2009/section3/vce_english_ga09.pdfStudy scores have a mean of 30 and standard deviation of 7, so a 35 would place you around the top 76%. A 35 from there is just solid work throughout the rest of this year, and maybe a few A's in remaining SACS and the exam?
As for studying for it, I guess practice essays and get feedback from a person that isn't your current teacher if you think she isn't doing a good job. Study the contexts/themes/ideas and just read plenty of examples etc and learn from them. That's what I'm doing atm.
Read and write as much as you can, I guess.