Are you sure it's over?
This is one question you really want to have clear in your head before you do anything. Unfortunately, there is no easy way of figuring it out - it's simply something you must answer for yourself. Discuss the situation with close friends that you can trust and write down a list of things that you are unhappy with to help you get your head straight. You should also be asking yourself whether this is someone you can see yourself spending time with when you're old and whether they still make you feel special.

Straight down the line
If you're doing the finishing, there are right ways and wrong ways to do things and although you may no longer care for this other person, there's no need to humiliate or embarrass them. This is someone you've spent a lot of time with and perhaps still care for. A good idea is to try to picture how you would like to be treated if the situation was reversed - which is surely not to be told by phone, email or, god forbid, text.

Don't be a coward. Things should be done face-to-face and sorted out sooner rather than later - no one wants to be strung along, wondering why it feels like the relationship is fizzling out. Even though you can never be sure how they will react - chances are, it won't be pretty - knowing that you dealt with it decently will mean you won't be dwelling on your bad behaviour later on. And neither will they.

Be honest
Whatever you do, try to avoid such old clichés as 'It's not you, it's me'. Although this might be easier, as might be a few white lies, the only way you can help them to understand why you are breaking up is to be as honest as you can. Sure, there's a fine line you want to try to follow: being informative enough so that the person understands it's over, but to stop short of making them feel they are being criticised or attacked.