@hansel According to what i've read about the process up to now-> If you want to qualify from Education qualification, then you have to pass the
3 main subjects in A/Ls. A/L Passed means passed, they don't look at
A/L General English or O/L results or Degree Masters, PHDs to reconsider you.
If you don't qualify the ^above requirement, then you should have a job which should meet
job category to job zone 4 > and svp range 7-8 (just Extracted from above). Even my job (related to information security and auditing) have a margin level according to their marks. (I just checked to verify whether i'm secured on this category also).
So my advice is to
Read about that scoring much more from Britsimon's blog and US web site. Verify for sure that you'll qualify. Even you feel you'll qualify, confirm it from the embassy also
before paying for interview.