Prepare yourself mentally. Just because you're hearing German words and phrases, doesn't mean you won't understand them. You can and you will!!
Revise lots and lots of vocabulary before the listening exam.
Make the most of your reading time beforehand. Use this time wisely and don't spend all your time trying to translate the first question. Make sure you make a mental note or even underline the question word in each question so that you do not give someone's name when the question is asking you where something is.
Make notes in the margin as you go along. If you are really stuck, write down what you have heard as it sounds to you. Come back to it later and try to work it out.
Don't assume that the first thing you have heard is the correct answer.
If you are not careful, you may find yourself merrily writing down "Fußball" because you are so overjoyed to have understood a word. Listen to the whole conversation before you write your answer.
Listen out for clues for tenses. If you hear "gestern" or "letzte Woche" or a verb beginning with "ge-", the person is referring to the past. If you hear "nächsten Sommer" or "morgen", the person is referring to the future.
A very obvious one: if the question is in German, answer in German. If the question is in English, answer in English! You'd be amazed how many people throw marks away.
Look out for false friends. e.g. eine Apfelsine isn't an apple, apple juice or apple pie, it's an orange!
When drawing conclusions, listen to the person's tone of voice. Are they happy? Bored? Excited? Disappointed? Listen out for words like "nicht" or"kein" or "nie" which would make their comments negative.
Finally, try hard not to leave any gaps. It is always worth a guess and you won't get any marks for a blank space.