For Moulds and mildews to grow, they need a moisture source, a food source and a bit of warmth. The best method of control is by reducing the food and water sources for Mould. The food source for most of these Moulds is our own skin cells and the soaps we use. The phosphates found in some soaps are also a great fertilizer for this growth. Keeping these residues at minimum levels will reduce potential Mould growth.
To reduce moisture, you could use a squeegee or a towel to wipe down the walls of your shower after every use. I'm not quite that motivated; in my home I leave the bath door wide open after a shower to allow the humidity to dissipate and this seems to work for me. Running a bathroom exhaust fan also helps pull humidity out of the room.