If you are not yet versed in the terminology of your subject you can use a number of resources when coming up with search terms:
Dictionaries
Thesauri
A thesaurus is also called a synonym book. It is a publication used in a similar way to a dictionary, but for looking up synonyms. During your studies, the following two digital thesauri are of interest:
You can use the thesaurus function in MS Word while writing your report. This is under the "Review" tab.
A thesaurus belonging to a database. Subject-specific databases are particularly interesting for this purpose. For more information see thesaurus.