Generally: choose subjects that your daughter finds interesting, that she may read at Uni (if that's an option) and that may be useful to her future career.
First and foremost, study subjects that she is interested in. A levels are very different to GCSE and require a genuine e interest if you are going to do well.
is you daughter more of a scientist or a humanist? Essays or calculation etc? That should be reasonably obvious. Maths is a subject that straddles both but remember its a big step from GSCE to A level. Good teachers should ensure an A at GSCE, but a genuine maths skill and interest are required for the step up. Ditto languages.
Languages are a great idea, if they suit your daughter, as fewer and fewer students study them. It may not get her better/ easier offers for Uni, but it will increase the chances of getting them in the first place.
If she is an artist/humanities person be careful not to over burden with too many heavy reading subjects eg, history and english
Does a likely career require certain subject? Does a likely degree require them eg economics and maths? Check Uni admission centres to see how they compare different subjects as they are becoming more discriminating about softer subjects ("studies" in the name 😉 )