Greek uses a different alphabet from English (and you may already know some of the characters, like alpha, delta, omega), so that's the best place to start. You can also learn some basic words and phrases for the environment where you expect to be using the Greek language, whether that's to travel or to speak to your second cousins overseas. English has borrowed many words from Greek, and it might help to find ones that are already familiar to you and learn to use them with the Greek alphabet and pronunciation.