I went from 670 Q48/V34 to a 760 V48/Q48 in one month.
I ended up spending way too much $$ on test prep. The most effective materials for me were
Magoosh for the math, Manhattan for SC, and reading the news for CR/RC. GMATNinja has the best free videos on SC as well as some of the free veritas prep videos for advanced SC. I never tried
TTP.
Magoosh has some great free videos on math too, the matrix methods were awesome for me. I ended up paying for a
magoosh course which was a waste of time and money, if you're shooting for a 700+ (you all should be, you can do it) the course won't cover the really hard questions. Don't worry about timing when you are learning, the speed will come.
The biggest mistake I made was using the practice questions before I studied. It was a waste of time and questions to practice. If I were to do it all over again I would take a full-length timed diagnostic test first, focus on your weak areas then take practice questions in those area when you feel confident. If you're taking the GMAT you are probably ok at quant and all it takes is relearning some formulas and problem solving strategies. SC were completely new concepts to me and I'm a native english speaker.
I started studying with
Magoosh and the official practice problems for a month then I got a 670. Honestly, I could have gotten a higher score except my schedule is insane and I had to be out of town the night before the first test. I rescheduled the next one a month later and buckled down on verbal. The next test I cleared my schedule outside of work for a week and was able to prepare mentally the week leading up to it. I strongly believe prioritizing my physical wellbeing that week had the biggest factor in being able to earn a high score. Also if you absolutely rock at quant then take verbal first, the mental fatigue is real and makes it harder to comprehend what you're reading especially if it's those nasty 700+ SC questions.
Outside of test prep material, sleep is your best friend. Have the right attitude! Before I took the GMAT I set myself the goal of getting a 720, I came from a not elite undergraduate university and I thought I would be happy with just above 90%. That goal doomed me to failure, shoot for the stars. Seriously it doesn't matter who you are a 760 is possible if you set your mind to it.
Go study.