First, educate yourself about what a vegan diet entails and why it is beneficial to your health. You need to understand and embrace the philosophy or you will not be able to make such a drastic dietary change. Secondly, make the change over time. Don't try and "go cold turkey"; you will shock your system and you will develop cravings that you may not be able to fight off. If you take your time and let your body adjust you will be eating a completely different diet before you realize it.