Proof them before the first wear. Suede is just leather with the nap raised, and that nap drinks water and stains. A waterproofing spray before you ever step out, refreshed every few months, is the single most useful thing you can do for a pair.
Brush, don't wash. Keep a suede brush by the door and give them a brush after each wear to lift the nap and knock off surface dirt. Always brush dry — water flattens and darkens suede while it's wet.
Lift marks mechanically. Scuffs and shiny patches come back with a suede eraser or a gentle rub of a crepe brush. Grease spots respond to a little talc left overnight to draw the oil out, then brushed away.
Dry naturally and reshape. If they get caught in the rain, blot don't rub, stuff them to hold their shape, and let them dry completely away from heat before you brush the nap back up. A re-proof afterwards restores the water resistance the soaking stripped.