Take one of the digital Information Skills courses provided by the University Library (UB). You can find them on the website of the UB (www.eur.nl/ub/english) under 'Instructions'. These courses offer efficient strategies and techniques for searching for and processing scientific information, digital or otherwise. You have free access and you can do the course whenever you like during your studies.
While writing try to keep a record of all the steps you take. Save the results of your searches and save bibliographic information in a document or database program.
Software such as RefWorks (www.refworks.com) or Endnote (obtainable at the Erasmus Shop and Surfspot) can be helpful in this process. Instructions can be found at www.eur.nl/ul_instruction > References and citations.