Tips to break 700 in Math SAT (680 right now)

Hey guys so I usually get a 660-680 in the math section of the SAT during practice tests which is usually due to the last two to three hard questions in each section and a miss of one or two grid ins. How do I work on getting these hard questions right so I can break 700 and possibly get to a 750? How should I study/practice in order to reach this goal.

I have the Blue Book
Grubers Math SAT Workbook
PWN the SAT Math
Dr.Chungs