You have many ways to improve the quality of your images
Enhance your prompt by using "Enhance prompt with details"
Change or add more details about your models
Click on preferences icon on the right side of the selected model
Do image variations
Image variation can be very useful when you want to locally iterate on a result.
Upscale and enhance
Upscale and enhancement can be very useful to improve a generated image, correct some artefact, and denoise it.