Do not begin any detailed original study until you have read some secondary works on the subject. It is better to approach original material with some ideas about what has already been written on the subject. Make sure you note down full details of authors, titles etc of any works you read and note the page numbers of any useful sections you may wish to quote or cite. This saves a lot of time trying to find your sources again when you write up your work. Devise and keep to a system of taking notes that suits your style of working.
Some people prefer to keep separate cards for each item, quote, fact etc.
Others use ordinary sheets of paper marking different items or writing them in different colours. Think about what suits you best. If you can afford it, take photocopies of especially useful pages or sections of works you use. This will enable you to mark or underline parts and cut down on extensive note taking. Writing your Dissertation Try to begin writing drafts of sections or chapters early - even if you still have more reading to do on other sections.