yangayev wrote:Today, on 19th December, I took gmat and got 620 (Q50, V23). And I was shocked. Since I reviewed all prep materials, I was sure that for that time I could crack the GMAT. But the result is so poor. But I never give up. Please experts, need help. How to organize next prep. I intended to retake after 30 days.

Well from the look of it you have a pretty solid grasp of Quants. I think you'll need 4-6 weeks more to prepare for the verbal (the obvious culprit here). Well you can reduce the prep time depending on the score you have in mind.
There are many options available:
1)MGMAT SC and RC Books can be one source (but their stuff is very thick.
2)Magoosh Verbal has a few good reviews (though I haven't tried it myself)
3)E-gmat verbal course (good one; but you have to search for practice material)
4)GMATPill SC and RC Pills (again!not tried but have heard lack practice material).

As for practice material you have a lot of it here and on gmatclub.com. And while you are at it, don't forget to keep working on your Math (just to keep the good shape).

This is just my humble opinion, lets see what our more experienced members has to say.

Thank, you very much.I listed through a few of all the sources, but on test day I found the questions structure, logic a bit strange, a little different from the source we have at hand. Maybe it seemed to just me. Now I am in a distress. From what start.