Hello Tushan,
I was in the same situation like you, I suffered a lot for Toefl, at the 4th time I got 102, before that I had 90 and 91 in USA and 86 in India...here is my experience...
You can't improve yr english within a month...Its a long process, so start from today not only for Toefl, but also for yr future communication in this english speaking country...
Practice Writing essays, here I have attached one site that guides u for essay writing...its really good, before that I wrote many essays, but haphazardly...It teaches you how to write essays systemically...
My speaking is bad too. So, even after passing my Toefl, I try to improve my speaking, so it will help me for better communication in future...In below attached site, you can hear sample answer, answers by registered students and comments by experts and I think you can also submit yr answer, its great!!! buy headphone, if u don't have one, download voice recording software and practice on your own...listen it 2 times and recognize yr mistakes, try to minimize that in yr final exam...
watch news and English movies, in between if you don't get any word, just try to look it in dictionary.com and also find similar words...
http://www.english-itutor.com/TOEFL_iBT.html
http://www.cz-training.com/toefl/improve01.html