Tell your friend as soon as possible. Putting off the inevitable will just make them feel worse and give them even less time to get used to the idea. Keeping the information to yourself will make your friend feel betrayed and lied to.

Find the right time to tell them. Over the phone, online, or via text is a terrible way to unload big news. Go out for lunch or drop by and tell them in person. Be sure it's a time when you have each other's undivided attention.

Use tact. Lead up to the big news by talking about why you need to move and your friend will sympathize whether it's a new job, new school, to be closer to family or whatever your reasons may be.

Tell them that you're moving and how soon it'll be happening. Wait for their reaction. You've had more time to get used to the fact that you're moving away, and they are just now hearing it.

Mention how important they are to you, and how much you want to stay in touch after the move. Discuss if you'll be calling once a week, emailing, or even writing letters. Make your friend feel included and tell them that they'll have to visit often. It can be scary to let somebody go, and so reassure your friend that you still want to be important in each others lives.

Think about their feelings first. They may react to this news in any number of ways, but no matter what, they'll feel sad that you won't be close by anymore. Be prepared for them to act a little differently towards you for awhile. It's not that they like you any less, they just need time to readjust and let you go.