The emergence of generative AI sparked thoughts on how it can be helpful across the stages of fashion design practice and creativity. We investigated the potential impact of prompt engineering using stable diffusion and Midjourney on understanding the relationship between the prompt and outcome, and how it influences the final process, thinking, or result. Our study provides guidelines for designers to use specific formats and words to describe the garments to generate clothing designs even if they are not familiar with text prompt engineering. We found fashion designers more likely to focus on the clothes and the overall feeling that the images evoke, meaning that anatomical accuracy is not their concern. This research is a rare exploration that combines prompts engineering with fashion, providing insights and recommendations on how to better utilize AI as a tool in industry.