How to pick a PhD topic? I have been offered an opportunity for a part time PhD in Computer Science. I have had brief conversation with the person that would be my advisor. He has suggested that I start to think of a topic/proposal.

I literally have no idea where to start, what level of detail I should be looking at for a proposal?

I have read a couple of the articles on this site like: How to find a good topic for a PhD research proposal? 

These all offer great advise. Maybe I'm missing something but I am starting to feel a bit overwhelmed already!

One idea I have had is modelling student success based on different factors like: home environment, past student success, etc.

All I keep thinking of is the advisor said "It needs to be something new".

I guess any advise on creating a research proposal, picking a topic, where to begin... would be great.
You mentioned the problem: "It needs to be something new". That's not only highly unspecific, but also extremely hard to gauge by a prospective PhD student.

Sure, you can start reading articles/conference proceedings and try to find interesting questions (e.g., what these authors mentioned as open questions). But in my experience, you need to be working in a domain/field to really get an idea which questions/problems are interesting and worth-while to answer/solve. After all, the research the papers are based on is usually at least a year old and conferences proceedings aren't that much up-to-date. So the person who likely can tell you whether something is new is your adviser, if s/he is actively doing research. A good adviser, who is part of the research community (visits conferences, works with other researchers, does peer-reviews for journals and conferences) should know what the other researchers work on (and thus reduce the risk that you get scooped half-way in your thesis) and guide you where you can make a contribution.

If you really want to work with this adviser, one way would be to check his/her publications and look for interesting topics/open questions. You could go from there and state your interest and ask him/her for possible directions where you can take his/her previous research. While the work has to be new and it must be your work, in my opinion it really helps to have a content expert to get started and to get good feedback. After all, I would consider a PhD an apprenticeship, not something you should do solo.