Primary sources require a little more analysis than secondary sources, but if you put in the work you'll arrive at a fresh perspective on past events. No one will interpret a source in exactly same way and there isn't one right way, but primary source can be misleading if you don't read them closely and think about the context in which they were created. Here are some questions to get you started in interpreting a primary source.
The physical nature of the source
The creator or author
The historical context