Look at the Assignment
Some are designed to help students learn new information or expand their thinking on an issue. For these, academic conventions are often less important than showing what you've learned or thought about. Other assignments are designed to help students learn what it's like to write within the context of a specific discipline. For these, academic conventions are extremely important.
Does the assignment specify using outside sources? If so, can interviews and field research be included or just library sources? Does the assignment indicate whether you can use personal experience or critical analysis? Most professors who expect to see personal experience or thinking on an issue say so pretty clearly in the assignment sheet.
Do you have to follow a specific format? If so, what are the section headings? These can be used to help identify the kind of material you will need to generate. Does the assignment note specifically the level of formality? Does it, for instance, note that you should write for possible publication in a journal?
Does the assignment specifically note expectations about proofreading? Often, a professor who reminds students about taking care with punctuation and spelling is asking for a more, carefully edited paper.