Might not be a huge help, but:
1. Know your vocab. It is essential that you have a good load of vocab stored under your belt for the exam. Also, make sure you know which gender, declension/conjugation it is.
2. Know your grammar/syntax. This is where most people fall in Latin, as you have no hope translating a sentence correctly if you do not know the basic/foundational grammar skills that Latin revolves around.
3. Know your English. The worst things that can happen in a Latin exam is when you know how to translate a sentence, but your translated answer is either convoluted or just doesn't make sense in everyday English usage.
4. Know what you are being examined on. Sometimes it can be hard to conjecture what the Latin exam may entail (i.e. Unseen) but that just comes down to vocab, grammar and English skills again!
This is all I can think of at this stage.