www.apachediver.com
that's where i did my open & advanced. very friendly folks.
yah, monsoon season is either approaching or is
here, though it's more likely of the latter. So popular spots like
tioman and pulau aur will be closed to you. the season will reopen
in march (i think? not sure)
& yah, i'd oso recommend that newbies not dive in crummy
singaporean waters, where there is very little to see, if you can
see through the water @ all. it's much more worth it to go that
little farther north and see what you always see in the catalogue,
crystal clear water! 
on a side note, has anyone dived in thailand since the tsunami?
how's the place like now...?