The way to keeping suede shoes clean is this simple method: dry first, water last.
Start with a regular brush. Take the dirt off the top with short brush strokes. If the stain goes deeper, wet a towel in some warm soapy water. Massage out the stains and leave things to dry. Once the shoes are dry, spray your shoes well with water resistant spray.
For deep, stubborn stains, repeat the process using a steel brush first..