A great place to start any research project is with an encyclopedia. Use Britannica's database to search for your scientist for some basic information to get started on your research. http://school.eb.com/levels, choose the level you are most comfortable reading at keeping in mind that the higher the level the more details in the entries.
Here are some other useful links to help in your research:
Biography.com offers a whole page on famous scientists. http://www.biography.com/people/groups/famous-scientists
Another good resource that focuses on the lives and achievements of histories most famous scientists and inventors is http://www.famousscientists.org.
Developed by Eric Weisstein is an alphabetical listing of many famous scientists. Just click on the letter of your scientist's last name. http://scienceworld.wolfram.com/biography/letters/
You can find a short list of famous scientist biographies at http://www.ducksters.com/biography/scientists/scientists_and_inventors.php.