Different fabrics require different care. Cotton and linen are both natural fibers, but using the same techniques on both will result in the material losing quality over time.
Caring for Linen
Use a delicate detergent and low spin speed. Make sure to take out of the washer ASAP, because it can mildew. It's best to dry linen on the clothesline.
Pay attention to the care label of the clothes, but as a matter of course, cotton withstands most washing and drying cycles extremely well.
How to Wash Denim
Although denim originated in France, it's truly an American workhorse. Typically, denim is a cotton fiber. Wash your denims separately though, especially the first time you're washing them. Don't wash at high temperatures and use a slower spin speed, if possible. Normal drying with a gentle option is recommended.
How to Care for Wool
Check the label for precise information about the wool blend that you need to clean. Some products should be dry cleaned, while others can go for into a gentle, quick wash. It's best to lay sweaters flat while drying. Soil and dirt can usually be removed from the wool by brushing with a garment brush or damp cloth. It's best to let wool fabrics get a 24-hour rest between uses.
Wash silk fabrics separately from any other kind, because they are quite delicate. Use the gentle option on your washing machine or hand wash with a gentle detergent. Dry at a low temperature and if you must iron, do it while the fabric is slightly damp with a low iron. Silk does not like high temperatures.
Washing and Caring for Blended Fibers
Many materials are blends of two types of fibers, perhaps cotton and Lycra, a synthetic fiber, or cashmere and cotton. When washing and drying, use the directions for the most sensitive fiber in the blend. Typically, you should use a delicate cycle and dry on a lower temperature. The care label will give you information about the fibers in the material.