Good advice from Gregorius above. The other big thing to think about is funding. This is often the factor that limits you getting on a PhD program. You need to consider whether there is departmental funding, whether you will apply to an external source (with a supervisor), or whether you will self fund (which I don't recommend in general).
It's a bit unusual to choose a university to do a Masters and a PhD (unless it a combined program). You should choose a Masters based on the course, university, staff etc. Your choice of PhD university depends on the specific project you want to do, a supervisor who is an expert in the area and the availability of funding. People often apply to many different universities and supervisors before finding one that will accept and fund them. So targeting one specific place before a Masters is not always the best.