This is where things typically "get complicated" but it doesn't have to! Even on our subreddit, there is an overwhelming amount of troubleshooting. Consider that for every post asking for help, there are three other people who have found what works for them. No one posts, "Hey everyone! Just successfully completed my 3rd load of diaper laundry this week!" - though they might on Suds Saturday!
Keep in mind that each child, washing machine (or lack of), and situation is different.
When first establishing your wash routine, head on over to Fluff Love University's Washing Machine Index. The machine machine index fond on FLU is a good resource, and while it shouldn't be taken as gospel, it's a place to start.
The general recommendation is two (2) wash cycles.
"Prewash": a short or normal wash cycle on the heaviest soil and highest spin with 1/2 the amount of detergent
"Main wash": a heavy duty or normal wash cycle on the heaviest soil and highest spin with the full amount of recommended detergent (according to the amounts recommended on your detergent bottle).
Each machines have their own settings and cycle names, but your specific machine will have wash routine that works best.
When starting out, use the detergent's recommendation for heavily soiled loads for a full load of diapers (half that amount in the prewash). It is not necessary to add boosters.
Do not use fabric softener or dryer sheets. These can coat the diapers and cause repelling.
If you have hard water, you'll want to use a water softener.
The two most popular are Borax and Calgon. A good rule of thumb is a capful of liquid Calgon in the mainwash or half a cup of Borax. If you have very hard water (<250 ppm), you may need to use softeners in the rinse cycle too.
Some commercial detergents (i.e., Tide) contain water softeners already and they can manage in hard water (~150 ppm).
How you dry your diapers depends on manufacturer recommendations.
Most diapers can be tumble dried on medium. That said, air-drying can extend the life of the diapers. The majority of people tumble dry absorbent parts and line dry covers and pocket shells.
Pro Tip: "Sunning" is a popular way to remove stains. Simply line-dry your diapers outside and let the sun work its magic.
Pro Tip: Avoid stretching the elastics while the diapers are warm. This will wear them out faster.
Wool does not need to be washed often. The lanolin that is used to make the soaker waterproof has antibacterial properties. If the cover is not soiled, simply let it air out until dry. Every 2-3 weeks or when it begins to smell when dry, it's time to wash.
Hand wash knit wool with soap designed specifically for washing wool such as Eucalan or Unicorn Clean. Felted wool may be machine washed on a very gentle wool cycle. To hand wash:
Fill a bucket with warm water and recommended amount of soap
Submerge your soaker until it is completely wet and let it soak for 15-20 minutes
Squeeze the soaker so some of the water and soap passes through it (no need to scrub). Let the diaper soak another 15 minutes if it is extra dirty
Rinse the diaper by filling the bucket with clean water, submerging the diaper another 15 minutes and squeezing it until the water runs clear
Squeeze most of the water out (don't wring it)
Roll it up in a dry towel to remove excess water
Lay it flat to dry
If your diapers smell after they have been washed and dried:
Contact your diaper manufacturer for wash routine recommendations
Check your washing machine manual
Reach out to the /r/clothdiaps for advice, either in a daily thread or making a stand-alone post.
Head on over to the "Troubleshooting" page for more thorough tips and tricks, and the FAQ.