Have a look through the threads on this board. There are many threads on here that have asked the same question you have asked. It doesn't really make a significant difference if the advice is for someone doing French at Continuers level or Extension level. Follow the advice given there and you'll find the answer to your question, but, just in case you are pressed for time or just plain lazy, the best ways, in my experience, for you to improve your French to earn a band 6 is to-
1). Read a lot of French, especially French in the formats that you will be tested on for writing i.e. letters, emails, postcards etc.. You can find this stuff in French textbooks such as Tapis Volant, which should be available at your school or local library. If not, you can go to Abbeys Bookstore in the city and buy one, though if you are pressed for cash I recommend you buy a French novella such as
Le tour du monde en quatre-vingt jours or
Le Pétit Prince instead, which should cost less than $20.
2). Get a good French dictionary, verb conjugation book, and grammar book. I recommend these-
http://www.bookdepository.co.uk/Collins-French-Dictionary-Grammar/9780007323159
http://www.bookdepository.co.uk/Blue-Pocket-French-Verbs-David-Stillman/9780071421638
http://www.bookdepository.co.uk/Ultimate-French-Review-Practice-David-Stillman/9780071744140
Read through the verb book and grammar book at least through once. You don't need to take notes from them and you don't need to do all the exercises (I recommend you don't do them at all because you won't have the time to finish them all. Just read.). Just remember where particular sections about grammar or verbs are in the book and refer to them when you are having trouble with understanding something about French grammar.
3). Go to the following site.
http://www.tv5.org/TV5Site/enseigner-apprendre-francais/accueil_apprendre.php
Instructions on how to use this are in another thread on the French board. You'll find it.
4). Watch movies that are dubbed in French with French subtitles.
5). Learn French songs by listening to them while also following the lyrics. It's just repetition. Here are some good songs that I think you will enjoy-
[youtube]JVmwtcJKdZw[/youtube]
[youtube]IcmG8eeanaY[/youtube]
[youtube]f5shipypasU[/youtube]
[youtube]PaUI6Tvd1sA[/youtube]
[youtube]c53iVBzdBiY[/youtube]
6). Do as many writing tasks as you can from the writing tasks sheets you got from OHS and hand them in as quickly as possible. Don't leave it to the last minute. You don't really need to do the R and R sheets, unless if you are bad at it, but writing is the most important as it will also help you in speaking.
7). Read aloud in French. It helps. You can also record yourself to see if you're speaking with a good accent.
Cheers. And just out of curiosity, who is your teacher at OHS?