Pre-Wash: Brand new diaper repel moisture rather than absorb it. Make sure that you wash 3-4 times before using. There can be residue left on the fabric from the production process that can cause leakage. Reduce the amount of detergent to 1/4 of your normal amount. Detergent must be completely dissolved for optimum washing results.
When I got my diapers, I immediately had them washed twice in hot water with very minimal detergent. I used Cycles. I know you should always follow the manufacturer's instructions and it said to wash it 3-4 times but I think it's a waste of time and resource, so I opted to use hot water and wash it twice and I think it works just as well. I also made sure to line dry them under direct sunlight for optimum clean.
The diapers I bought were bamboo and you shouldn't wash them together with your diapers lined with microfleece or suede because the oils from the bamboo will coat your microfleece and result in leaking.
To prep cloth diapers:
Wash them in hot a couple of times with very little detergent (Cycles, 1/4 cup to 15 diapers) line dry under direct sunlight.
To prep bamboo and hemp:
Boil some water in a pot then put your bamboo inserts in when the water has reached boiling. Boil for 15mins.
I did the same with my Hemp inserts or run them through several washings (but like I said, I think it's a waste of resources) Boiling is faster. This is to get rid of their natural oils and it help make them more absorbent.
I didn't boil my shells though, (yikes!). I just washed them in hot a couple of times before use then wash them as I normally would cloth diapers. It's a good thing they're all bamboo!
(Cloth diapers usually come with washing instructions and if they don't, I hope this post will help.)