As Year 12 students get ready for mock exams, here is some great advice from Jo Messer.  The full article is well worth a read, you can find it at careerfaqs.com.au.  
1. Most people don't know what they want to do when they finish school - it's normal!
2. Your marks don't define your course or career choice.
3. There is more than one road to the same destination (e.g., bridging course).
4. You need to be aware of what your influences are (family, friends etc).
5. If you take a year off, use it wisely.