With today's modern detergents there's often no need for prewashing. If there are stubborn spots on the garment, it is better instead to use a spray-on spot remover before washing.
Always use colour detergent on coloured garments, and carefully follow the dosage instructions on the detergent packaging. Do not use detergents containing bleach (e.g. perborates, percarbonates, and sodium hypochlorite). Always use the correct detergent for the wash temperature stated on the garment washing instructions.
Drip or tumble dry? Almost all garments fare better with drip drying. Shake out the garment, straighten the seams out and hang it up. If you do tumble dry, be sure you do not totally dry out the garment. The majority of shrinkage and the worst wear in tumble drying take place when the garment is almost dry.
Your JOBMAN Workwear garments will have symbols on the tags that will guide you to the proper laundry procedures for that item. Here is a legend of these symbols.