Getting Clobbered by GMATClub Math Practice Test

I'm writing the GMAT for the second time on June 1. First time around I got 690 (Q43/V41). Overall I did OK, but I'm hoping to get into a top teir program.

I've been doing a few of the GMATClub practice math sections - which I highly recommend - but seem to be getting crushed particularly on number property data sufficiency questions.

It seems there's always a little detail that I miss.

I don't really have any specific question per se, but was hoping for a moral boost, and a bit of a break by posting here.

Anyone else really struggling with number properties. I have trouble "picking good numbers". I often jump jump to conclusions, which is clearly what the test designers are hoping the test takers will do.

I studied engineering, so I'm used to "problem solving" and seem to do significantly better on PS Qs. Data Sufficiency gets to me, because in engineering it's all about making safe assuptions (like things not being 0). I'm having to unlearn habits to try to get a good score.

C'est la vie...