You have to make sure that you know all the basic quant concepts and their applications before you do any JJ. JJ is important but it is just a portion.
you have to change the way you read. Think while reading. Get the big picture instead of hang on the details. I am afraid that you will freak out if you lose your pace during the test. Speed up RC and CR. Simply put, you have to finish an article in the required time! ETS sets the pace, not you.