The most important thing is to get English and maths (compulsory) Then, if they like science, they need their science (2 sciences will be compulsory, if they are good at science, this is their best subject, then make it 3 sciences)
If there is a subject they like a lot, and may want to do it for A level, eg if they love geography/French
Then be aware that art GCSEs are a lot of work. great to to if you are artistc and enjoy art, but think about it due to the amount of work.
DT is less work intensive.
I disagree about group work, if they love drama, go for drama.
It is good to have one GCSE which is more practical, it gives them a variety in the week, instead of all book work.
Given all that, what is your dc good at, and what do they like?
Don't worry about universties looking at GCSE results. It helps to give them a sense of how clever they are and they basically look at the top 7 results and what the grades were, they are not intersted in the details.
my ds (year 11) did - 3 sciences, DT business studies, French, Geography
my dd (year 9) has just chosen 3 sciences, German, Drama and computer science
Both lean towards sciences/engineering