If I was writing a step by step guide I would first do the paper plane by myself. I would record myself and attempt to describe everything I am doing. I would try to include close-ups of difficult parts or different angles in a picture in picture manner if necessary. Once I feel confident that everything is explained correctly, then I would use my family or some friends as volunteers and present the guide to them and see if they can follow along. I would encourage them to ask questions after a number of steps to make sure the are still paying attention and there’s no confusion. Finally, I would encourage them to ask me any questions at the end and if they have any recommendations to improve the instructions. Giving them a survey to complete after the instruction ends is a good way of getting their feedback and saving it for later reference.