Stains
Treat stains as soon as possible, if only by immersing in cold water.
Always start with the simplest method of removal first - i.e., try cold water first, then move on to stain removal products.
Try to remove it before washing by soaking it in cold water and then a solution of lukewarm water with a gentle detergent.
Remember that the stain must be removed from the fabric's surface - be gentle and try to avoid driving the stain further into the garment.
Test the method you will use on a part of the garment that doesn't usually show, and then it doesn't matter if it makes it worse.
When treating a stain, always work from the edge of the stain towards the centre, or you'll spread the mark even more.
If all else fails, take the item to a specialist dry cleaner.