Here's a version of my “simple workflow” for illustrious. Its purpose is to make it easy for you to generate images from another image. It includes an upscaler sampler to add details during upscaling.

Resources you need:

Files :

• An illustrious model : like this one
  in ComfyUI/models/checkpoints/

• An upscale model : like this one
  in ComfyUI/models/upscale_models/

• As many LoRAs as you like (optional) : like this one
  in ComfyUI/models/loras/

Custom Nodes :

• ComfyUI_UltimateSDUpscale

• ComfyUI-KJNodes

• ComfyUI-mxToolkit

• ComfyUI Image Saver

• rgthree-comfy

• ComfyUI-Custom-Scripts