@slinkyme
This is what we did for choosing which universities to look at:
Once they know which subject they want to do, you can start narrowing it down.
First look at the average offer from each university. There's no point looking at A*AA universities if your child is likely to get BCC, and vice versa.
Once you have a list of universities that are the right level for their ability, they can narrow it down further.
Neither of my older two want to study in London (too close to home and living costs too high) or more than 200 miles away. Your child might have strong preferences about whether or not they want to be in a city, or at a campus-style university.
By now, you should have a list of about 10-20 places. At this stage, I encouraged them to look at the specifics of each course. They can either do this themselves, looking at each university website, or you can find out for them (if they are busy and you have time). For my older two boys, I printed out the list of modules for each course, and anonymised it so they could consider each course on its own merits without being influenced by the name of the university.
This brought the list down to under 10 places, at which point we started looking up dates of open days.