Well, I crammed for 5 days back in May and got a 36 (10vr 12ps 14bs). I'm sure if I allocated more time and resources I would be able to hit 38-40.
Basically if you are in a competent bio/chem UG program (e.g. biochemistry / pharm / microbio), your BS score will automatically be high, at least 13+.
Have a knack for physics and math, and the PS score should be able to get 13+ as well.
Assuming you nail those two and get 14 in both, then you "just" need a 12 in VR. That is probably the toughest part since different people handle VR with different degrees of finesse.
Personally I didn't study for VR at all, so my score of 10 in it was dumb luck and common sense. With some actual practice + some semi-regular readings of journals and such, 12 should be attainable. A friend of mine got 13 on Verbal, he can't even speak and write English properly since he's a relatively new Chinese immigrant to Canada, but he had tons of article analysis practice from having to do TOEFL tests just in the previous year, and also he is a highly analytical and observant person in general.
So tl;dr is be in a bio/chem focused UG program, like physics, and practice tons for verbal, and you should be able to hit 40 with a dash of luck.