The Graduate School hosted a Research and Fellowships Week panel on the applying for international research fellowships and opportunities. Current USC PhD students working on dissertations that require travel and research abroad offered this advice on applying:
I want to dispel the myth that you have to have the perfect proposal. The reviewers of your application know your research will morph.
Utilize or organize writing groups within your department and workshop your application with your peers.
Have non-academics review your application to ensure that it is readable by everyone.
Writing fellowship applications is not separate from your research project. They are mutually reinforcing and mutually beneficial.
For more Research and Fellowships Week activities, find the schedule at: http://ahf.usc.edu/rfw
The USC Graduate School has a lot of resources for students looking for fellowships. A Fellowships and Awards database was recently launched at http://awardsdatabase.usc.edu/.