Doing some secondary source research before you begin looking at primary sources will help the primary sources make more sense.
Check out books as well as online articles.
Keep a list of key players involved in events related to to your topic.
Keep a list of key events and dates.
Make note of nicknames, slang terms, alternative forms of names related to your topic.
Put this list on a laptop, phone or other device so you can have ready access to it.
These links will take you to resources about Environmental History. Many of the Web resources contain both primary and secondary sources. Looking here is a great place to start if you are searching for or refining a paper topic.
GALILEO : collection of over 400 research databases, including:
Historical Abstracts Index and abstracts to articles on world history 1450 to present (excluding U.S. and Canada).