Your GPA is good for Ph.D program. Most schools seldomly give out Assistantship to International Students for Master program. What you should do is to keep up your GPA, but you should concentrate more the research aspect. Get some research experience this summer. Find out the professors at the schools you want to get into, get familiar with their research and contact them. You can have a 3.8 GPA but no clear interests on research, you still can get rejection. In graduate school, its all about research, and knowing what you want in your research. Even your recommendation letters should reflect the major aspects of your academic ability: as a student and as a researcher. Hope this help