These are just some examples of the settings I usually use and it's not really a hard requirement so you're free to experiment and see which setting works best for you:

Sampling Method: DPM++ 2M Karras or DPM++ 3M SDE Karras
Sampling Steps: 20 - 50
Hires. fix: On (optional)
Upscaler: ESRGAN 4x+ or 4x_NMKD-Siax_200k
Hires Steps: I usually put it at 0 so it'll be the same as Sampling Steps
Denoising Strength: 0.2 - 0.3
Upscale: 1.5 - 2
CFG Scale: 4.5 - 6

Extra Tips

Try to keep the prompts short and concise. No need to fill up the prompts with unnecessary wording that does the same thing like high detail, ultra detail, absurdres, hires, photorealistic, hyperrealistic, etc. Keep it simple.
ADetailer is kinda optional for this one unless your faces are really far away and distorted. But it does help adding extra details to your character's faces with things like lines, shading, eye details, eye color, face contour, etc. Use either face_yolov8n or mediapipe_face_mesh..
Use negative embeddings instead if writing paragraphs of words into the negative prompts. Here are some examples of the ones I usually use: