Well given your current scoring level, I think you really need to focus in on the basics. I have heard many people say that a good high school math book is the best place to start. Once you have a solid handle on the basics, you should probably work with the OG, go through it in its entirety, and review the explanations for each answer, even those that you get right. Once you can work through the OG and get 95%+ correct, you can then move on to the questions posed on the math forum
here at the GMATclub and to the challenges offered here. As you go along, you should probably gauge your progress with the GMATprep software. You can use it over and over again, but you will have some repeat questions. I did them 3 times each and found the useful.
For verbal, you should not start with the LSAT questions. You should use those once you can get through the OG questions with 90%+ accuracy. I'm also a fan of the old paper tests, though I don't know that other people like them. The reality is that if you are shooting for a 200 point improvement over 570, you'll need to score 95%+ on both Q and V.
I will point out that you have a tough road ahead of you to achieve your goal. We have seen reports of people gaining 200 points on their GMAT, but it usually involves a lot more than 2 months of hard work. I believe that GMAC reports that fewer than 1/100 people that re-take the test gain 100+ points. To look at it another way, you'd be moving from the 61st percentile (about 84,000 people will achieve this or better this year) well into the 99th percentile (approx. 500 people will pass 770 this year).