Before you start writing, having a good sense of what you'll be writing is an important first step. Some examples of text types that require different kinds of writing are:

• a paper: you look for the answer to an objective research question through field research or a literature study. A paper contains an introduction, methodology, your results and a conclusion
• an abstract: a short, objective summary of the contents of a scientific publication. An abstract contains an introduction, methodology, your results and a conclusion. If it's in lieu of a research proposal, you naturally don't have to provide results or a conclusion.
• an academic poster: a visual representation of your research
• a research proposal: you convince the reader that your research question is important and you present how the research will be conducted. A research proposal consists of an alluring title / research question, an abstract, an explanation of your research and a list of references.
• a review: you present your personal opinion in a scientific manner. Start by contextualising: a short introduction of what you're reviewing. Argue the strong and weak points of what you're reviewing and illustrate with literature or examples. Draw a conclusion.
• an essay: this is common on written exams. When asked to respond with an essay, you answer the question in a structured, critical fashion, in a short, clear text.
• a summary: a structured rehash of the main points of a text. A summary also includes a conclusion.
• a synthesis: one summary of different texts. Connect the different texts with eachother.