i frankly think u're nuts...
firstly, mindef is in "paper" mode these days... no paper
qualifications, be prepared henta kaki...
secondly, mindef is especially in scholar mode these days... they
take care of the careers of their scholars (and why shouldn't they?
they've spent a fortune educating them!) if u're not one of them,
be prepared for many frustrating moments when u think that u're
just as good as them, but your chance is lost cos u're not one of
them. it may or may not be true but it will eat u inside out and
piss u off plenty if it ever happens...
thirdly, unless u're thinking of doing it for the long haul... i.e.
straight in from NS, first contract, second contract and work all
your life, then retire with a fat bonus, don't do it. u stay in for
one contract, u feel tempted to stay on forever... at 30, u really
don't wanna risk too much by starting all over, esp if u've got
family...
fourth, u only aim to be an officer. its the only route that pays
properly. but because u've only got a diploma, be prepared to henta
kaki even if u get there... u may not even get captain. rarely they
do, but u never, ever get major.
fifth, keep your options open... many other places other than
commandos can prove just as rewarding in many ways. unless u like
pain in massive doses, i seriously don't think its a good idea to
go in and end up hating it... the regulars in there are really
extreme 
they usually screw their limbs before they're 30... kneecaps,
elbows, back, u name it, they've cracked it... its physically very
intense but these people have proven that its "mind over matter"...
and they'll keep going if they can because their career depends on
it and they really like doing it... its beyond my comprehension ...
