This is designed for dev (which I much prefer over Schnell), if you are using Schnell just drop the steps to 4.

Update: Added new version that has the FluxGuidance and ModelSamplingFlux nodes. Flux Guidance seems to be like CFG, too much and the images look overbaked, too low and they loose detail and structure. No idea what ModelSamplingFlux does yet.

If you haven't set Flux up yet follow this and make sure your ComfyUI install is up to date.  https://comfyanonymous.github.io/ComfyUI_examples/flux/

It's colour coded for blocks. The first block is green and is for prompting. There are 2 options here: Manual Positive Prompt as per standard or BilboX PromptGeek and Portrait Master. There's a switch at the right also in green, set it to 1 for manual prompting and 2 for BilboX/Portrait Master.

The next block is in purple and is for the Flux generation. I've set the weight type in the Load Diffusion Model node to fp8_e4m3fn and the clip_name1 in the DualClipLoader node to t5xxl_fp8_e4m3fn so it should run on most systems, I have a 3090 and 64GB of system RAM so I've set clip_name1 to txxl_fp16 on mine. I recommend leaving the weight type as it is as my generation times take much longer when that is set to default.

There's then a couple of bright orange nodes (so they're easy to spot), an input switch and a fast group bypasser. These are for choosing the Upscale method, AuraSR (I'm using v2) or UltimateSD. Set the switch to 1 and turn off the UltimateSD group to use AuraSR and vice versa to use UltimateSD. I'm using AuraSD as it takes around 30 seconds and UltimateSD takes around 30 minutes with no real difference in quality. I left UltimateSD in for anyone who likes to tinker but it's switched off by default.

For AuraSD you will need to create a folder in the models folder in your ComfyUI directory called Aura-SR and download models.safetensors and config.json from here  https://huggingface.co/fal/AuraSR-v2/tree/main  and put them both in that folder. As I found out when I first tried it, it will not work without the config file in there.