Many diapers have restrictions on the type of detergent you can use. Soaps with perfumes, surfactants, enzymes, and other additives can effect how some fabrics (such as PUL) perform. Check before selecting your product. I personally recommend making your own detergent such as this one because it's cheap, eco-friendly, and very effective.
Prior to washing diapers, it's prudent to remove as much of the solid waste (that's poo!) as possible. Some use a diaper sprayer or disposable liners. Find what works best for you. (Here is a quick, easy method without use of a diaper sprayer or liners.) After most of the solid waste has been flushed, wash all diapers in a cold wash. This can be one of the quicker/more water & energy efficient cycles because you will follow up with a hot wash. Use minimal detergent with all washes, but do use some soap with both the cold and hot cycles.
After the cold cycle is complete, add more detergent (not too much!) and start a hot wash with extra rinse. The extra rinse helps get rid of any soap buildup and keeps diapers from getting stinky.
Ideally cloth diapers are dried on the clothesline in the sun. UV rays help eliminate stains and smells. You may tumble dry on high heat if line drying is not an option. Some covers and pocket diapers are better left to line dry even if indoors and not in the sunlight. This will extend the life of certain fabrics, such as PUL.
Lanolizing Wool Covers/Soakers/Longies
Due to the antibacterial and self washing nature of wool, covers/soakers/longies do not need to be washed often at all. If and when the cover becomes saturated with pee, simply turn inside out and hang to air dry. If the cover becomes otherwise soiled (poo again!) rinse in the sink and turn inside out to air dry on the line. You'll notice with time (apx 3-5 wks use) the covers become less water repellent and may leak or smell. This means it is time to lanolize.
You may do so with wool wash that contains lanolin (such as Imse Vimse Wool Shampoo.) Do not ever use soap or detergent on your wool products that does not specifically state that it's safe for use on wool.
Alternatively, to lanolize: boil 1-2 cups of water. Add water and 1 teaspoon of lanolin to a small jar with a lid and shake to dissolve lanolin. Meanwhile, soak wool items in about 8 cups of warm water then add lanolin mixture. Gently stir and swish to evenly distribute lanolin. Let items soak overnight for best results. Roll items in a towel to remove excess water and hang to dry.
Items may feel sticky and greasy to touch immediately after lanolizing. I find this generally goes away after 1st use (and baby's legs get a great moisturizing!)