Now the funny thing is that even after finishing GRE I sometimes get people asking me what was that that helped me get a good GRE score (well, at least my friends are surprised).

Now, I didn't do anything extraordinary. You might check the article on How To Improve English Speaking - it speaks on this topic in detail.

Yes, I went to classes and they really helped. But what helped me even more was that I constantly visited urch forums and practiced Big Book tests.

I know for sure that without extensive practicing I would not be able to be even confident to get a 1450 score.

Relax and do your best. :)