As an international applicant, I would recommend against getting a masters from anywhere except one of the top (1-3) schools in your country. A master's from university in the top 30 in the US or one of the top schools in UK/Canada are also options.
If you are not yet competitive for a top master's program, I would suggest trying to get a job as an economics research assistant, ideally with a well known professor. This has the advantage also of giving you a better look at what economics research looks like first hand, which is closer to what you'd be doing as a PhD student and professor than your classes in a masters program.
Ultimately to be competitive for a top 10 school, you absolutely need a high GPA and GRE, and then on top of that you need letters of recommendation from at least 1 or 2 professors that are respected in the field, ideally who have a track record of placing students at top PhD programs. Even then there seems to be a lot of noise in the system about who gets accepted where.
I posted it in a comment above, but to reiterate, I think this is very good advice. http://faculty-gsb.stanford.edu/athey/gradadvising.html