The easiest way is to store your contacts in your Google Account. This way, you can just sign in to your Google Account on your new phone and your contacts will be synced to your phone.
There are also other ways for transferring contacts:
1. Transfer: Use the Transfer app to transfer not only your contacts, but also calendar events and text messages from your old phone to your phone.
2. Social network accounts: Log in to your favorite social networks to import contact information from them.
3. SIM card: Import all your SIM contacts to your phone.
4. Microsoft Exchange ActiveSync: Sync your work contacts from the Microsoft Exchange ActiveSync Server in your workplace.
5. Sync with your computer: Sync the contacts from your old phone to your computer, and then use HTC Sync or HTC Sync Manager to sync your phone with your computer's Microsoft Outlook, Outlook Express or Windows Contacts.