I've been browsing for a few weeks now and just signed up for the GMAT on May 29th. I'm targeting a 700+ score (who isn't). I took the GMATPrep test last week with no preparation at all and score a 500 (Q 35, V 23). It was definitely lower than I expected, but at the same time I had no preparation and it was the first time I've done anything scholastic in 3 years. I'm confident I can get a 700 with proper studying and preparation. Below is my current basic study plan (partially borrowed from a few posters).

11-12wks total
2 hours per weeknight (except Friday)
10 hours per weekend
Starting with Quant (PS for 2 weeks and DS for 2 weeks) and then on to Verbal (2wks per section)
Doing 40 questions per week of previous sections
Using OG 11th Edition - 40 timed questions per night

I'm still devising a strategy for correcting weaknesses. Right now I'm just trying to re-learn a lot of the basics and get myself in study mode.

I'm planning on purchasing the Manhattan practice tests. Is it overkill to take 1 practice test per weekend? I wondered if it would be beneficial since I haven't studied every section yet. Also, I'm considering an online course to supplement my training. Would I gain anything with that course that I wouldn't get from going through OG 11, MGMAT tests and studying on my own? If I don't do the online, I would likely get the 8 Manhattan study guides. Thoughts?

Any other suggestions or advice would be greatly appreciated!