Generally speaking, you should include a reference whenever you use a piece of information that is the idea/work of another person.
It is very important that the reader of your work is able to clearly distinguish between the ideas/work that belong to you, and the ideas/work that you have obtained from others.
So, generally speaking, if the information did not originate via your own thought processes, and cannot be considered 'common knowledge', then it should be referenced.
There may be occasions when you are not sure whether a piece of information should actually be considerred 'common knowledge'. The general recommendation is that if you are in doubt as to whether a piece of information really needs referencing, then it is better to reference it.
There is no need to be concerned that including numerous in-text citations will make your work look unoriginal. Your tutor will mainly be interested in the way in which you analyze your source information, and build your own opinions, arguments and conclusions.