For a reader who has not done this before but who is at least generally familiar with the subject, describe thoroughly how to accomplish one task, probably a step of a larger task. This could be mechanical or kitchen-oriented or sporting or artistic; however, it will be important to narrow your choice to one significant action, not the entire task. Rather than describing a whole tune-up or baking a complete pie, or how to snow board or throw pottery, choose how to change a spark plug, how to roll out a pie crust, how to put on the bindings for a snow board, or how to wedge clay.
Whatever topic you choose, it will be best if it's something you know how to do fairly well, or have learned recently enough to be able to offer insight to someone else. For instance, if there are common errors or things to avoid, make sure to include them.
You can build any 'thesis' sort of statement in as a topic sentence controlling your paragraph's direction, and any 'conclusion' as an ending transition into the next step.