I would say, make a list of the subjects that you like, or A-levels that you haven't done but might be interested in, e.g. Law or Psychology. Then maybe do some research about these and maybe rank them to see which ones you might be interested in doing: if you like it you're much more likely to do well.
If you're not sure on future paths, it's generally recommended to do Facilitating subjects. You've already got 2, being Biology and History, as they're well respected. Biology leaves you open for a career related to that, and History provides large access to many essay-based careers or degrees. If you enjoy it at the moment, one subject that might be useful would be Mathematics - it's very well respected, but leaves you open for many careers - for example, it's wanted for Computer Science, Finance, general Maths, even medicine. If you don't enjoy Maths, you could always consider another Science-y subject to leave your options open for that route more, or a more vocational subject such as Drama or Product Design. As you've already got an essay-based subject you're fine for that route.
However unless you do think you'd be interested in going into a vocational route, I would say that it's not generally recommended to do them: they're not generally considered Facilitating, as they only really help you get into that certain pathway, unlike the sciences which are looked well on for multiple routes.
Obviously, in the end, it's completely up to you. It's much better to do something you like and get good marks rather than doing something you don't like but think leaves your career-paths open, and get worse marks. Hopefully this helps, it's one of those things that's hard to give advice on, but this is what I'd generally say
. Best of luck with your GCSEs, and good luck wherever you go
P.S. as you're in year 10 at the moment, you've still got a while to choose - it might be worth asking teachers and such on what they think, or what their A-level courses are like, to get an idea of what you're getting into.