Feel free to ask Dhampy any questions. He is usually unbiased when it comes to most issues.
If you really want to start first you should choose whether you want to know about the Political happenstance of USA or you want to start as a General knowledge and idea.
As for your homeland then it's pretty easy to follow up the incidents and US political spectrum by reading even magazines and newspapers. For more a General idea on this matter i think you should start Basic structure and backbone of this science by reading the history of politics and it's evolution. Read history of Greece.
There are some books but since the authors are Iranian(I am Iranian)and text is in Persian i can't be more of help.
If you bumped into words which you had no clue search Wiki! There are great references posted in that site.