It is best to wash your diapers at least every 2-3 days. Any longer than that and they will start to smell!
First of all, Take a look at the detergent that you are planning to use. You will want one that has no heavy perfumes, dyes and no added fabric softeners (like Dreft). You also do not want to use laundry soap. The added fabric softeners and the laundry soap can cause the diapers to become moisture repellent (not what you want in a cloth diaper). I recommend a detergent made for cloth diapers or a simple detergent such as Lulu's in the fluff, rockin green or charlie's soap. And, don't use fabric softeners of any kind! Also, bleach is a no-no, and will usually void your warranty if there is one.
There are two methods for storing soiled diapers.
The wet pail - Keeping your diapers soaking in water is not necessary to keep them clean. A pail full of water can be a safety hazard to small children. The pail also has be on the small side or you will not be able to lift it. If you to soak, don't use detergent or bleach in the water and make sure that the lid on your pail locks.
The dry pail - Just dump any loose solids in the toilet, then put the diapers in a dry pail with a liner. On wash day dump in your washing machine. a sprinkle of pail freshener or baking soda will help with any odors.
Note: If you exclusively breastfeed, you don't even need to rinse your diapers! The breastfed poo is completely water soluble and will wash out easily. Once you add formula or solids, you need to rise the diapers in the toilet or use a diaper sprayer to get the excess poo off the diapers. No need to rinse wet diapers.
As for the wash cycle, I recommend doing a cold soak and rinse, followed by a hot wash and an extra hot/warm rinse to get any leftover detergent out.
Detergent needs to be completely rinsed out of all diapers each time. Detergent build up will trap old odors and that wonderful smell will be released when your baby pees. Only use half the recommended amount of detergent. (unless using a cloth diaper detergent, then follow the instructions!) Check the diaper load when you haven't added any detergent. If there is foam on top, the diapers have detergent built up in them. Run them through another cycle until there is no foam on top.
Drying your diapers
Diapers can be dried in the dryer on low heat, but hang drying is great for increasing the life of your diapers. Just make sure that you don't use fabric softening sheets!
let me know if you have any more questions!