Beer - Rinse or soak fresh stains in lukewarm water, then wash normally
Blood, egg, gravy, chocolate etc - soak in cold water and salt, then wash
Coffee/Tea - Wash in rich suds a.s.a.p.
Flowers/grass - Sponge with meths + wash
Grease/fat/oils - soak in detergent solution before washing.
Paint - (emulsions) sponge with cold water and then wash. (oil-based) dab with white spirit and then cold water + wash.
Pencil - boil the stains in milk, and wash.
Spirits (alcohol) - rinse with warm water and wash normally.
Wine - Soak and sponge in a warm detergent.