Hi crackgmat
You can go over posts in this forum. There are many useful tips given by our members. There is a guide about scores on our website. please check it out. you might be able to find some info there.
I will let you answer most of the questions here.
My first advice is dont worry about what the split has to be in order to get 670. focus on what your problem areas are. you have taken the GMAT once. you should have a fair idea about what your problem areas are.
Can you list them out for us or for yourself? after you do that, can do committ to solve and understand atleast 10 questions of each problem area every day. can you regularly maintain a log of your errors? Are you making a note of the errors that you make? do you see a pattern in your errors?
Pace in verbal:
SC:
I timed myself in my prep to solve every SC question within 45-60
seconds. I made a lot of mistakes, but after more practice, the timed practice gave me enough confidence to solve MOST of the SC questions correctly. why is this important? the faster you can correctly solve SC's, the more time you have for the RC and the CR, which are more time consuming.
RC & CR:
Practice, Practice and Practice and record your errors in a log. Study them every single day before you start your prep. After studying your errors, you will have come up with a strategy to solve these questions based on the specific problem areas that you have. how many to practice? practice until you have developed a fairly good strategy to implement on test day.
if you can tell us in detail about how you prepped, we might be able to help you better. the more detail the better.
Hope this helps
Sincerely
Praet