There are different methods to choose from, but one method is called the "Think Aloud" method. Don't omit steps or take shortcuts.
In-sentence lists are good whenever you give an overview of things to come. Carefully consider the technical level of your readers.
When you get to the actual writing of the steps, there are several things to keep in mind: 1 the structure and format of those steps, 2 supplementary information that might be needed, and 3 the point of view and general writing style.
Decide which word or term you will use to describe something and stick with that. Writing a work instruction is not about sounding clever. Try to fit all the steps on the same screen.
For example, asking what their experience level with the task is or what their job field is. Multi-syllable words sound brainy but slow the reader down. In order to single these specific users out, you may need to ask a few preliminary questions. Emphasise important information by using upper case, bold or italicised text.
Avoid multi-syllable words, complex sentences, jargon, acronyms, too many technical terms without explaining them and unnecessary blather. For most instructions, you can focus on tasks, or you can focus on tools or features of tools.