How to prevent style bleed when combining reference images in image-to-image workflows?

When working with reference-image workflows (single img2img or multi-image fusion), what is the most reliable way to separate what should change from what must stay preserved?

For instance, when feeding two or three reference images (e.g. one for subject pose/structure, one for style/palette, and one for background context), diffusion models often blend features unpredictably—such as lighting from the style reference bleeding onto the subject, or fine facial details getting altered.

Beyond adjusting prompt weights and boundary phrasing, what practical steps or preprocessing checks do you find most effective to keep control over the output before running iterative generations?