The method, in order
Start by brushing the whole shoe in one direction, following the natural lie of the nap. This lifts loose dust and dried mud and reveals what you are actually dealing with. Do not scrub in circles; you will muddle the texture and create patchy shading.
Next, attack the shiny or scuffed areas with the eraser. Press firmly and rub back and forth as though you were erasing pencil. Crumbs will form; brush them away and check your progress. Shiny patches are usually crushed fibres rather than dirt, so what you are really doing is roughing the surface back up.
For stubborn marks, use the rubber crepe side of the brush with short, brisk strokes. Then finish by brushing the entire shoe again in one direction so the nap lies uniformly. That final pass is what makes shoes look cared for rather than merely clean.
Only if a stain survives all of that should you introduce moisture, and even then, sparingly: a cloth barely dampened with water, or a specialist suede cleaner used exactly as directed. Work the whole panel rather than one spot, so you do not create a clean island in a dirty sea, then let it dry naturally and brush again once fully dry.
Specific disasters and what to do about them
Rain spots are best treated by dampening the entire shoe very lightly and evenly with a spray of water, then blotting, stuffing with paper, drying slowly and brushing. Even moisture removes uneven moisture marks.
Oil and grease need an absorbent, not a solvent. Cover the mark generously with cornflour or talc, leave it overnight to draw the oil out, then brush the powder away. Repeat if there is still shadowing; it often takes two rounds.
