  Scientific writing is an important skill for a career as a professional
astrophysicist. Very few researchers, however, receive any formal training in
how to write scientific research papers of high quality in an efficient manner.
This paper (Paper I) is the first of a two-part self-help guide in scientific
writing to address this skills gap. Paper I focuses on planning your academic
research paper in astronomy. We discuss how to crystallise the ideas that
underlie a research project, analyse how the paper can be constructed
considering the audience and the chosen journal, and give an overview of the
publishing process. Paper II is a detailed description of the different
sections that make up a research paper in astronomy and shares the best
practice in how to write in English. Whether you are a student writing your
first paper or an experienced author, you may find the ideas presented here
useful.
