If you use the careers approach, then by knowing what careers you're interested in, it'll be easy to decide by going backwards.
Career -> Degree Subject(s) -> Pre-University/A Level/IB/Year 12(+13) subjects -> SPM subjects
With the right combination, there could be virtually nothing you couldn't do... for example, if you studied Mathematics, Physics, Chemistry, and Biology, as well as written-based subjects (e.g. Literature) and languages in school, and also did music/drama/art/design outside of regular school work/examinations, you'd be set for any university subject.
If you're not that kind of person (most people aren't, that kind of person is extremely rare), then there are many similar (and still ambitious) approaches.
Some people take a wide combination of subjects which includes both things they enjoy (Biology, Geography, or Literature perhaps) as well as things they would need for Pre-U and undergrad (Pure/Additional Mathematics, Physics perhaps). This is easy if you're good at everything. If done well this approach reduces your future limitations.
Some people take subjects which are related/from a set, because they are good in them and/or are interested in them, and would likely need them in the future. If they plan well/choose well, they don't have any disadvantage.
Mathematics, Physics, Chemistry, Biology - these are a set of subjects you do not want to neglect (not as a whole) when choosing... because at least one or more of them are prerequisites for Engineering, Pharmacy, Medicine, Dentistry, Computer Science, Economics, Actuarial Science etc. In the event you aren't entering a degree that utilises or requires Mathematics or any of those Sciences, you would still be eligible for admission since these subjects are highly regarded (to an extent).
Business Studies, Commerce, Economics, Law etc - these are relevant but are never required. Taking any of these is important only for knowledge and interest (because any good student could get admitted for undergrad Econ/Finance/Accounting/Commerce/Law without any of these).
Literature, History, Economics, Law, Geography, Religious Studies, Politics, International Relations, Government, Sociology - these "written/essay-based" subjects are essential for those interested in Politics, Philosophy, Economics (needs Mathematics), Law, History, Sociology, Politics and Government, IR. However, they are not required, so choose carefully (do those that are relevant/that you're interested in). These are an important set of subjects for those who are absolutely disinterested in any degree to do with Mathematics or Sciences (vs soft subjects like Business Studies and Accounting, and of course Law).
Added on October 12, 2011, 6:49 pmQUOTE(Screen @ Oct 12 2011, 12:34 PM)
So if I have no intention to step in the medical field when in the future, theres no need to take bio?
Btw, wad jobs can be applied on these subjects:
1) Chemistry
2) Physics
You apply these to jobs, not the other way round.
Biology has applications in Chemistry/Biochemistry, Pharmacy, Pharmacology, and Psychology in addition to the other Medical/Biomedical and Life Sciences, other Health Care subjects (Optometry, Physiology etc), and of course traditional Biology subjects (Molecular Bio., Genetics, Zoology etc). If you're not interested in any of these, then (since you're clearly not interested in Biology) take something else.
Chemistry -> Materials/Chemical Engineering, Petroleum Engineering, Petrology, Geology, Earth Sciences, Pharmacology, Pharmacy, Teaching etc.
Physics -> Engineering (safe to say all branches), Physics Research, Quantitative Analyst jobs/Trading/Structuring/Hedge Funds (individuals highly qualified in Physics are sought after for their mathematical/quantitative skills), Teaching.
This post has been edited by LightningFist: Oct 12 2011, 06:50 PM