Learn How to Listen
Although in an interview situation you are trying to sell yourself (therefore talking about yourself is essential), it is also important to stop talking and listen to your interviewer. A conversation does not flow one way and you should be interested in what they have to say about the position you are interviewing for. Ask questions about the company, and show that you are genuinely interested.
Nerves can sometime get the better of us and make us blab on and on, we completely understand. So when in doubt, for every two sentences you say about yourself, stop and ask a question, then just listen.