Practice more.

I suggest you get the LSAT CR compilation.
www.aristotleprep.com. Dont worry. It is free.

Generally with assumption questions, the problem is that we tend to think what we know as probable general rules may not be assumptions. But in the context of the problem, that may actually be an assumption.

The best strategy is to first read the stimulus. Write down the premises and conclusions. Then ask yourself what are the foundations on which this stimulus relies. That will unearth a few things. Then read the question stem.

For assumption questions, before you read the answers, first try to prephase what the answer could be. If you get to a possible answer, then you can read the choices and if you see your prephased answer, voila you got it!

I would suggest you to go through OG assumptions questions again, and try to re-read all the options and the reasons behind elimination of each option. Undoubtly OG, provides the best explanation. But even you still have some doubts then follow notes from Manhattan Verbal, it will surely clear all your doubts.

One of the recent article which I went through is
https://www.beatthegmat.com/mba/2011/05/ ... ssumptions. Hope that helps.