Hey Kirti.
First of all, you have not made clear whether you're interested in a Masters or a PhD. I applied for a PhD and I can give you a perspective in terms of my opinion to make it to the top CS programs in the US.
GRE: In my opinion, the general GRE is of little relevance for a top CS PhD program, unless its atrocious. Anything about 2100, with an 780+ in Quant, and not anything lesser than a 4.5 and 500 in the AWA and Verbal respectively should meet the GRE bar -- if it exists in the first place.
TOEFL: I dont think this matters at all, as long as you can get something like 270.
A-GRE: I was of the opinion that of all the standardized tests, the subject GRE is the one that is given maximum weightage for the PhD programs. But having a good A-GRE score still does not ensure admission. Having a poor score however, could rule you out. Try to make around 75+ percentile. Subject GRE becomes even more important if your undergrad. school is relatively unknown to the admission committees.
GPA: Well, GPA is important to an extent. I know that all Department Rank 1s from my college have consistently made it to the top programs.
Research experience: This is an unstated, yet the most important factor for admissions in my opinion. Having one or two research papers could go a long way towards your admission at top schools. Having said that, this is probably the most difficult thing to do.
Anyway, good luck.