1) Maybe consider doing a lot of questions or get a tutor/teacher for extra help?
2)I don't think you can pick up a new subject in year 12...-as in, I don't think legal studies is one of those subjects you are allowed to pick up if you haven't done the preliminary component yet.
Below is an extract of my study guide which you may find to be helpful
-feel free to read the full guide here:
http://community.boredofstudies.org...how-excel-senior-year-studies-yr-11-12-a.html
My top 3 tips for preparing for excelling in science subjects (e.g. Chemistry, Biology, Physics etc)which includes the main types of assessments you will encounter in your senior school science courses.
1)PRACTICAL ASSESSMENTS:
Make sure you know reliability, validity, accuracy, sources of error, possible areas for improvement, independent/dependent/controlled variables, risk assessment for all the experiments you have done in class, make sure you can master basic science skills such as drawing line of best fit, drawing experimental set up accurately, using numbered points in writing a logical procedure, understand the requirements of the exam(I.e. how much time, how many parts) and allocate your time accordingly, make sure you understand the chemical principle/theory behind why you did each experiment
2)THEORY ASSESSMENT AND EXAMS:
Make sure you PERSONALLY write a set of summarised notes according to each dot point of the syllabus in a concise but detailed manner-make sure you include appropriate diagrams as well, after you wrote the notes, make sure to start practising questions and CHECKING YOUR ANSWERS in textbooks-i.e. Roland Smith's Conquering Chemistry has an exam question section which is quite good, ask your teacher for practice questions and make links between dotpoints and across modules to reinforce your understanding. Throughout the year, you should be progressively cutting down your notes as you store more things into your long term memory-revise regularly. Before your final trial exam-you should try to get your hands on as many preliminary exams as possible to practice-and look at the marking guidelines, remember to practice under EXAM CONDITIONS. Make sure when you make notes you are at least referring to 3 different sources to synthesise your information. (colour-code and use mind-maps to make your notes engaging and easy to remember). In your notes, don't neglect to include all your experiments and second-hand investigations.
3)OTHER:
For other types of assessments such as group presentations, individual research assignments, second-hand investigations-you should strive to always include a comprehensive bibliography that indicates you have sourced your information not only from websites, but from journals/books as well, you should understand how to evaluate accuracy/reliability/validity in relation to the sources of information you are using, like other types of assessment, pay close attention to the marking criteria and make sure you fulfil it as much as possible, make sure your information is comprehensive, non-repetitive and answers the verb of the question: i.e. discuss, evaluate, compare, contrast, assess, examine (so for that matter, memorise what the main verbs used in your exam questions means).
Essentially, to succeed in the science subjects(Biology, Chemistry, Physics etc), you need to understand, constantly apply your understanding through practising questions and adopting feedback from your assessments to do better in year 12-with repetition and consistent application you will achieve your desired marks.