First, open up Google Scholar.
http://scholar.google.com/schhp?hl=en&tab=ws&q= Then, I'd recommend searching the following...
"neo-colonialism"
"neo-colonialism" + "united states"
"neo-colonialism" + "united states" + "foreign policy"
"united states" + "foreign policy"
"capitalism" + "united states"
"capitalism" + "united states" + "foreign policy"
"hegemony" + "united states"
"hegemony" + "united states" + "foreign policy"
"neo-colonialism" + reactions
"neo-colonialism" + middle east
"neo-colonialism" + central america
"neo-colonialism" + latin america
"united states" + "foreign policy" + reactions
"united states" + "foreign policy" + middle east
"united states" + "foreign policy" + central america
"united states" + "foreign policy" + latin america
"united states" + "foreign policy" + southeast asia
Specific case studies you might want to use...
Iraq 2003, Kosovo 1999, Haiti 1994, Panama 1989, Nicaragua 1980-1990, Iraq/Iran 1979-1989, Grenada 1983.
On the individual level, apart from Bush... Reagan and Truman have been even worse in eroding US relationships with the rest of the world. It's just that they didn't do it as quickly, or with so much transparency. If you've read "The Bush Doctrine" (probably posted somewhere on this site), it's obvious that it is simply a combination and expedience of the Truman and Reagan doctrines.
You could also choose to focus on the international perception of recent domestic policy shifts toward arguable despotism, but I feel that this is less relevant as it has yet to fully develop.
While he leans toward radical leftism, Noam Chomsky's book "Hegemony or Survival" might be a good resource, as well as the entire series of "No-Nonsense Guides".
Goodluck.
PS- I assume that you have access to online periodical databases. I recommend writing down the names of the journals, volumes, issues, authors, and years, along with an abstract if available, of all articles that look interesting... (via Google Scholar)... then look them up later via whatever method you use to access electronic journal articles.