Well one issue is
OVER CONFIDENCE,
seriously people i remember somebody called me on the night of English papers 2007 and inquired
"why aren't you studying?"
Guess wot!
I replied "yaar ab
English mien aur kya parhun?"
This “confidence” was a major reason behind the fall of "attempt 2007"
So even if you think you are “too good”
give it a double check and re asses yourself by going through past papers etc.