When selecting a topic for your dissertation, try and pick a topic that you’re interested in (obvious!) but not too much (not so obvious). The reason is that if you pick a topic you’re "too interested" in, it can sometimes be difficult to find a way to narrow it appropriately for the scope of the dissertation. I saw this with one of my clients recently who is looking to develop a model of clinical intervention. She is really interested in this topic (good!) but is so attached to it that she’s having trouble deciding where to narrow her focus (not so good). The goal of your dissertation is to pick one aspect or one area that you want to know more about. If you are looking to finish up quickly, aim to research one question or a series of closely related questions-and stay away from designs that will require a great deal of "pulling together" of unlinked ideas/concepts. If you pick a narrow focus in a topic you like, this can make it much easier to follow this topic through to the end- a finished dissertation.