1. He has feelings too
I know that sometimes a partner may get very frustrated in the relationship, and feel like ending the relationship is the only method. But this doesn't mean that you have to be inhumane and rude. No need to scream, and name call if his reaction isn't just peachy after the breakup. He has feelings too, and the best way to end things is just to do it nicely and then get as much space as possible.
2. Timing is everything
When emotions are running high, you might feel like breaking up right there and then is the way to go, but make sure that it makes sense. For instance, is it worth it to break up with him right before a big exam? Or perhaps after the person had a terrible day? Regardless of your feelings karma will come back to you, so make sure the timing makes sense.
3. Make sure it's not your emotions talking
Often times a couple will fight and end things on a whim. Later on they will re-assess the fact that they may have been over-reacting and then end up together. But before they get there, a ton of unnecessary silence and suffering will occur. Make sure to really think about the consequences and what you want, when you're calm and not when the emotions are running high.