Ph.D/Grad Program in Political Science/International Relations - help!

<p>I am currently a junior majoring in political science and looking to go to grad school/Ph.D. However, I have very little idea about what getting into a top grad program entails and what factors they consider for admission.
With regard to that, I was wondering if someone could help answer these questions:
What do top graduate programs in Politics/International Relations look for?
Is there a cut-off GPA?
Do they expect students to have published research papers?
What criteria do they evaluate?
How do students prepare for entering such graduate programs?</p>