Black images issue:
2.1 models need to have a web-ui config modified - if you are getting black images - go to your config file and add to COMMANDLINE_ARGS= --no-half - potentially it could work with --xformers instead (if supported). This line might slow your generations a bit but will not affect negatively your output.
Prompt suggestion:
bichon havanese wearing sunglasses COLR_001, (((white background))), coloring book, line art, high resolution, black and white, colorless
Negative: ((watermark)), (text), color, shading, gradient, shadows, transparency, noisy, blurred