How to go to grad school for IR/government with little or no debt?

Hi all, I graduated from college last year with no debt, and would like to keep it that way. I’d like to get a master’s in international relations (or maybe another government discipline - I haven’t entirely decided), and I was looking at scholarship opportunities, including grants from universities and private organizations. I’ve heard that American University gives very generous aid to strong candidates. I graduated with a strong GPA from Harvard and think I could score well on the GRE, so hopefully I could qualify for something like that. Does anyone know more about which schools give strong merit- and need-based aid, private scholarship programs, or anything else I should know? I’ll be so grateful for any advice. Experiences from students who have been through this process would be extremely helpful.