Use the Internet as a starting-off point into your story. Research major sources, locations and prior coverage. Reading other people's take on a story is an invaluable way to spot gaps and places for further investigation.
Step2
Don't be afraid to contact authority figures in your investigation. While many will be willing to help you, those who don't also provide a helpful resource--they show you where to dig further.
Step3
If your investigation requires traveling to another location, establish an itinerary of places to visit and people to interview prior to arrival. Contact all potential subjects by phone several days in advance, and let them know you're coming.
Step4
Documentation is crucial. Obtain as much supporting evidence as you can by printing out web pages and articles, transcribing interviews, and taking photographs. Carefully divide these into basic categories for easy reference, and use them as both a resource and a way to check information given by sources.
Step5
Finally, rely on your intuition. All the information in the world won't replace your common sense of what's true and what's not. When you feel as though you've gotten the information you need, call it quits.
Authority 
Comments
writetruth said
on 5/17/2008 Very helpful! 5 Stars ~!~